390 
Proceedings of Royal Society of Edinburgh. [sess. 
On 25th April A. weighed 330 grms. and B. 230 grins. A. had 
11,200 and B. 7800 leucocytes per c.cm. Both were killed on 
5th October. A. weighed 870 grms. The thymus was completely 
gone. A small piece of splenic tissue weighing *67 grm. was 
found. B. weighed 550 grms. Thymus *55 grm., spleen -93. 
Experiment II. — A guinea-pig weighing 260 grms. had thymus 
('32 grm.) and spleen (*18 grm.) removed on 25th April. On 2nd 
May it weighed 290 grms. and had 6800 leucocytes. On 12th 
May it had 6600 leucocytes. On 2nd June it weighed 410 
grms. and had 13,000 leucocytes. It became pregnant, and aborted 
on 26th July, giving birth to three young, weighing in all 123 grms. 
It was killed the same day. The thymus was completely removed, 
while a small scrap of spleen was found. 
Experiment III. — Two female guinea-pigs had thymus and 
spleen removed on 2nd May. 
A. weighed 220 grms. . Thymus ’275 Spleen *345 
B. „ 280 „ . „ *280 „ -405 
On 12th May A. = 280 with 1200 leucocytes. 
,, B. = 3 1 0 „ 8800 
26th A. = 355 „ 5000 
„ B. = 385 „ 7200 
2nd June A. = 370 
„ B. = 400 
Both were killed on 6th June. Removal of thymus and spleen 
was complete. 
The number of leucocytes compared with that of normal animals 
of the same age showed the same slight diminution that we have 
noticed after removal of the thymus alone, but, as in the case of 
removal of thymus only, this leucopenia does not persist after the 
animal has attained the age of three months. 
Differential counts of the leucocytes showed no departure from 
physiological limits. 
We conclude that simultaneous removal of the thymus and spleen 
in the young guinea-pig in no way interferes with nutrition, blood 
formation, growth and development of the animal. 
