1890-91.] AMPHIBIA BLOOD STUDIES. 235 



fixed in chromic acid have in the unstained condition a greenish-brozvn or 

 broivnish-yellow color which he considers due to haemoglobin. This 

 color is maintained in the haematoxylin staining fluid while all the 

 nuclei of other cells become blue. I also have observed similarly 

 colored haematoblasts in chromic acid preparations, and I attributed 

 the color at first to the presence of haemoglobin. In such prepar- 

 ations, however, there are examples in which the chromatin elements 

 only are greenish-brown or brownish-yellow, and from this condition 

 to that where the brownish-yellow substance is so abundant as to 

 obscure the view of the internal structure of the cell there are all shades 

 of transition. This substance is not haemoglobin but rather an 

 antecedent of it, that is haematogen, and is of the same nature and origin 

 as the modified chromatin in the nuclei of the fully formed red cells 

 which also show the same greenish, greenish-brown or greenish-yellow 

 color when they have been treated with chromic acid. It differs from 

 chromatin in its action on haematoxylin and from haemoglobin in that 

 it is more easily fixed with hardening reagents in the cell, and in that, 

 as I will now show, it has a greater capacity for staining with eosin. 



In the preparations of the haematoblasts of larval Amblystoviata fixed 

 with Flemming's Fluid and stained, as described, with haematoxylin and 

 afterwards with eosin, one finds the modified chromatin or haematogen 

 stained very deeply with the latter reagent. The dividing haematoblasts, 

 according to this reaction, are separable into the following divisions : 

 (i) those in which the cell body is only feebly stained while the chro- 

 matin elements are stained deep terra-cotta red (Fig. lo) ; (2) those in 

 v/hich the cell body is only little less deeply colored terra-cotta red than 

 the chromatin loops (Fig. 1 1) ; (3) those in which the staining in the cell 

 body presents conditions transitional between (i) and {2). There can 

 be no doubt that in these forms the eosinophilous substance originates 

 in the chromatin. The haematoblasts are the only cells in such prepar- 

 ations which show this decisive eosin reaction. 



Now this modified chromatin or haematogen, as I prefer to call it, 

 when once secreted into the cell of the haematoblast persists there 

 through all the divisions of the latter. This certainly cannot be proved, 

 and I believe it is impossible to prove, but it is a reasonable inference 

 from facts gained by a careful study of the preparations. After a 

 certain stage in larval life, nearly all the haematoblasts show it to be 

 present and it is converted into hcemoglobin when the cycle of divisions has 

 been gone through. After the formation of haematogen once commences 

 it goes on, with the result that each of the numerous daughter or 

 descendant haematoblasts possesses by inheritance and through secretion 



