516 Dr. J. E. Lane-Claypou and Prof. E. H. Starling. [Feb/ 12, 



Interval of 10 days, owing to failure of supply of pregnant animals. 



March 



17. — 7 foetuses, etc., 



at 16th day. 



33 



21.— 5 



33 



26th „ 



33 



23.— 8 



33 



22nd „ 



33 



24.— 14 



33 



14th „ 



;■> 



25.— 12 



33 



20th „ 



•i 



27.— 5 



33 



20th „ 



33 



28.— 8 



33 



22nd „ 



33 



29.— 5 



33 



21st „ 



33 



30.— 7 



33 



17th „ 



3? 



31.— 4 



33 



20th „ 



April 



1.— 9 



33 



13th „ 



33 



3.— 9 



33 



18th „ 



33 



5.— 5 



33 



15th „ 



33 



6.— 11 



33 



16th „ 



33 



7.— 6 



33 



18th „ 



This rabbit, therefore, received the fluid extracts of the viscera of 160 foetuses. It was 

 killed on April 8. On reflecting the skin of the abdomen, the mammary glands were seen 

 to be markedly hypertrophied. The margins were almost contiguous, and were somewhat 

 raised and pink, presenting, therefore, much the appearance which is seen in a pregnant 

 rabbit of the eighth or ninth day. The general aspect of the stained gland is shown in 

 fig. 4. On microscopic section not only was there marked duct proliferation with mitotic 

 figures, but at the thickened border the formation of alveoli was just commencing. The 

 whole of these injections had been made intra-peritoneally, or, on one or two occasions, 

 under the skin of the legs, so that there was no infiltration of the connective tissue 

 surrounding the mammary glands. This is the best result which we obtained. 



Experiment 11. May 2 to June 1, 1905. — In this experiment we sought to determine 

 whether the growth-producing substance is contained chiefly in the viscera or in the body, 

 i.e., muscles, skin, and bones, of the foetus, and, moreover, whether it could be extracted 

 from these tissues by boiling. Unfortunately, however, out of the four rabbits which we 

 chose for this experiment, only two were definitely virgin, so that the results in the other 

 two cases were equivocal. 



Rabbit 1. not a virgin, received the pressed juice of the visceral 



Rabbit 2, a virgin, received the filtered boiled extract of viscera. 



Rabbit 3, also a virgin, received the pressed juice of the bodies of the foetuses unboiled. 



Rabbit 4, which was evidently multiparous, received the boiled extract of the bodies of 

 foetuses. From this rabbit, at the commencement of the experiment, a small portion of 

 mammary gland was taken as a control. 



All four rabbits received portions of 182 foetuses of all ages between May 2 and May 31. 



From Rabbits 1 and 4 milky fluid could be expressed from the nipples after the ninth 

 injection. 



In Rabbit 2 a watery fluid could be expressed from the nipples after the seventeenth 

 -injection. 



Rabbit 3 showed traces of watery secretion after the twelfth injection. 

 All four were killed on June 1. Results were as follows : — 



Rabbit 1. — Multiparous. Mammary glands well developed and showing many alveoli 

 on microscopic section. The ducts were full of milk ; they were, however, lined with 

 only a single layer of epithelium, and it was impossible to say that any hypertrophy had 

 taken place. 



Rabbit 2. — Virgin. The mammary glands did not present much enlargement as judged 

 from inspection. On microscopic examination, however, many branching ducts were 



