SILKWORMS, variations of. -yielding white cocoons, less liable to disease.
SILVER-GREY rabbit.
SIMON, on the raising of eggs of the silk-moth in China.
SIMONDS, J.B., period of maturity in various breeds of cattle. -differences in the periods of dentition in sheep. -on the teeth in cattle, sheep, etc. -on the breeding of superior rams.
SIMPSON, Sir J., regenerative power of the human embryo.
Siredon, breeding in the branchiferous stage.
SISKIN, breeding in captivity.
Sivatherium, resemblance of the, to Niata cattle.
SIZE, difference of, an obstacle to crossing.
SKIN, and its appendages, homologous. -hereditary affections of the.
SKIRVING, R.S., on pigeons settling on trees in Egypt.
SKULL, characters of the, in breeds of dogs. -in breeds of pigs. -in rabbits. -in breeds of pigeons. -in breeds of fowls. -in ducks.
SKULL and horns, correlation of the.
SKYLARK.
SLEEMAN, on the cheetah.
SLOE.
SMALL-POX.
SMITER (pigeon).
SMITH, Sir A., on Caffrarian cattle. -on the use of numerous plants as food in South Africa.
SMITH, Colonel HAMILTON, on the odour of the jackal. -on the origin of the dog. -wild dogs in St. Domingo. -on the Thibet mastiff and the alco. -development of the fifth toe in the hind feet of mastiffs. -differences in the skull of dogs. -history of the pointer. -on the ears of the dog. -on the breeds of horses. -origin of the horse. -dappling of horses. -striped horses in Spain. -original colour of the horse. -on horses scraping away snow. -on Asinus hemionus. -feral pigs of Jamaica.
SMITH, Sir J.E., production of nectarines and peaches by the same tree. -on Viola amoena. -sterility of Vinca minor in England.
SMITH, J., development of the ovary in Bonatea speciosa by irritation of the stigma.
SMITH, N.H., influence of the bull "Favourite" on the breed of Shorthorn cattle.
SMITH, W., on the intercrossing of strawberries.
SNAKE-RAT.
SNAKES, form of the viscera in.
SNAPDRAGON, bud-variation in. -non-inheritance of colour in. -peloric, crossed with the normal form. -asymmetrical variation of the.
SOIL, adaptation of plums to. -influence of, on the zones of pelargoniums. -on roses. -on the variegation of leaves. -advantages of change of.
SOIL and climate, effects of, on strawberries.
Solanum, non-intercrossing of species of.
Solanum tuberosum.
SOLID-HOOFED pigs.
SOLOMON, his stud of horses.
SOMERVILLE, Lord, on the fleece of Merino sheep. -on crossing sheep. -on selection of sheep. -diminished fertility of Merino sheep brought from Spain.
SOOTY fowls.
Sorghum.
SOTO, FERDINAND DE, on the cultivation of native plants in Florida.
SPAIN, hawthorn monogynous in.
SPALLANZANI, on feral rabbits in Lipari. -experiments on salamanders. -experiments in feeding a pigeon with meat.
SPANIELS, in India. -King Charles's. -degeneration of, caused by interbreeding.
SPANISH fowls. -figured. -early development of sexual characters in. -furculum of, figured.
SPECIES, difficulty of distinguishing from varieties. -conversion of varieties into. -origin of, by natural selection. -by mutual sterility of varieties.
SPENCER, Lord, on selection in breeding.
SPENCER, HERBERT, on the "survival of the fittest." -increase of fertility by domestication. -on life. -changes produced by external conditions. -effects of use on organs. -ascent of the sap in trees. -correlation exemplified in the Irish elk. -on "physiological units." -antagonism of growth and reproduction.
SPERMATOPHORES of the cephalopoda.
SPERMATOZOIDS.
SPHINGIDAE, sterility of, in captivity.
SPINOLA, on the injurious effect produced by flowering buckwheat on white pigs.
SPITZ dog.
SPOONER, W.C., cross-breeding of sheep. -on the effects of crossing. -on crossing cattle. -individual sterility.
SPORES, reproduction of abnormal forms by.
SPORTS. -in pigeons.
SPOT pigeon.
SPRENGEL, C.K., on dichogamous plants. -on the hollyhock. -on the functions of flowers.
SPROULE, Mr