2S6 Kojima 



part large and of nearly equal size. The cells are also large, although 

 there are a fair number of smaller cells amongst them. The cell- 

 nuclei vary in diameter from 3-7/x to dju ; a few of them are as large 

 as 10^. Both nuclei and nucleoli stain blue b}^ Mallory and deeply 

 by h^ematoxylin. The chromatin granules of the nuclei are coarse 

 and abundant. Many of the cells contain vacuoles of various size. 

 These are most marked in the animals which were fed with fresh 

 sheep-thyroid. The vacuoles, as is generally the case, are not 

 uniformly distributed, but are confined to particular portions of the 

 pancreas. Zymogen granules are plentiful in all the alveolar cells. 

 There is no evidence of mitosis, and no apparent change in the islets 

 of Langerhans. 



Summary. — After feeding for about a month with the ordinary dose 

 of thyroid mitoses are no longer seen in the pancreas, and zymogen 

 granules have again become plentiful, but there is still considerable 

 vacuolation of cells, especialh' in animals which were fed with addition 

 of fresh gland. 



Is the Active Substance or Autacoid extracted by Water, 

 and is its Activity abolished by Boiling? 



The next experiments were designed to determine whether (a) extract 

 of thyroid made with water and (b) the residue which is left after such 

 extraction produce the same effects as feeding with the whole thyroid, 

 and further to determine whether boiling desti-oys the active substance. 



Two sets of observations were made : one with addition of sheep-thyroid, 

 the other with ox-thyroid (see Tables XI. and XII.). The rats, eight in 

 number, were divided into four groups — A, B, C, and D. To make the 

 extracts, fresh glands, after being freed from the surrounding connective and 

 adipose tissue, were minced, and left standing for an hour in a definite 

 quantity of distilled water. The fluid was then filtered. The filtrate was 

 divided into two parts: one part was added to the food of A group with- 

 out boiling ; the other part was boiled and added to the food of B group. 

 The remainder left after extraction with cold water was repeatedly washed 

 with fresh water, which was decanted off: the residue was then divided 

 into two parts. One part was given unboiled to C group, whilst the 

 other part was boiled in a small quantity' of water and added to the food 

 of D group. 



The amount administered was equivalent to 4 grm. of fresh thyroid 

 per rat per diem. 



Sheep-Thyroid. — In the animals of groups A and B which received 

 the water-extract of sheep-thyroid no special symptoms were observable 

 except a slight decrease of appetite. In the animals which had the residue 

 there was slight diarrhcea from the fourth day onwards, as well as 

 diminution of appetite. After five days all were killed (on July 26). 

 In all the groups the iodine reaction in the urine was positive during 

 the feeding. 



