EQUIVALENCE OF HEMATOl'OIETIC ANLAGES. I. SPLEEN 271 



during the first twelve hours is put in the incubator, the window 

 down. This secures a closer contact of the tissue introduced 

 with the surface of the allantois. Next day I usually changed 

 the position of the egg in directing the window above. The 

 strict observance of the directions given secures usually 80 

 per cent of successful cultures. Interesting results in the form 

 of diffuse growth of transplanted tissue were obtained by intro- 

 ducing an emulsion of the tissue mash between the allantois and 

 the chorion under the eggshell. The whole allantois appeared 

 in a few days covered by innumerable small grafts. The same 

 results were occasionally observed also after applying the usual 

 method of grafting. 



Tw^elve hours after transplantation, the tissue is usually in 

 firm contact with the allantois. Later it is attached by nunier- 

 ous vessels growing from the allantois into the tissue. For fixation 

 of the material, it is advisable to free and fix first the embryo 

 after a ligature of the vasa umbilicales is done ; then to cut out a 

 large piece of the shell in the region of the culture. The allan- 

 tois which covers the shell is transported in the fixing fluid 

 together with the shell and is removed from the shell 5 to 10 

 minutes later. The fixation of the allantois and of the graft is 

 completed in ^ to 1 hour in Zenk.- formol. The celloidin was 

 successfully substituted by the parloidin Dupont, and I may 

 recommend this product as being in no way inferior to the 

 celloidin Schering. The imbedding in celloidin or parloidin 

 remains a sine qua non for hematological work, what easily 

 was deduced by a study of a few specimens imbedded in paraf- 

 fine last autumn (1915) when no more celloidin was available. 

 Since the staining of preparations attached to the slides and 

 freed from parloidin is more effective, it may be permitted to 

 recall the method of Rubashkin (36), somewhat modified by 

 Danchakoff (9, '08d). 



The greatest part of the material was stained by eosin-azur 

 and some of the preparations by Domini ci and Pappenheim. 

 For the staining of fibrous tissue the iron-hematoxylin and 

 subsequently van Gieson were used. Most of the illustrations 

 are given in black on account of the special temporary conditions, 



THE AMERICAN JOURXAL OF ANATOMY, VOL. 20, NO. 3 



