APPENDIX I. GROWTH OF RABBITS. 



THE data which I have collected concerning the growth of 

 rabbits have not been published hitherto, and are therefore 

 printed here. It is from the average of the percentage incre- 

 ments that Figures 35 and 36 were constructed. 



There are certain precautions in making weighings, not only of 

 rabbits but also of other animals, which were found necessary. 

 As soon as a litter was born and the amniotic fluid dried off from 

 the fur of the young, each individual was weighed, the sex noted, 

 and an exact description of all the .markings, which do not alter 

 after birth, written down. The litter was numbered, and the 

 date of birth and the parentage, or at least the maternal par- 

 entage, recorded. 



To identify the rabbits they were marked with spots of nitrate 

 of silver. It may be mentioned in passing that the Guinea-pigs, 

 of which there was a large number raised, can usually be indi- 

 vidually identified by their natural markings. I found it a 

 great convenience to give mnemonic names to all the pigs 

 of which I followed the growth, so that the name would sug- 

 gest the appearance of the individual pig. For the most part 

 the names referred directly to the marking, for instance, " Brown 

 rump," "Saddle back," "Snout," etc., but often the allusion 

 was more remote, as for instance, "Hypocrite," whose head, 

 seen from one side, appeared entirely black, from the other, en- 

 tirely white. The record having been started, the next thing 

 was to enter in a diary all the dates during the remainder of 

 the year upon which the litter in question was to be weighed. 1 

 The plan adopted after a little experience was to weigh each in- 

 dividual every day up to 40 days, then every fifth day up to 215 

 1 The apparatus devised for calculating the required dates mechanically is 

 described in Appendix VI. 



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