8o HOWELL. [Vol. IV. 



what seems to be an arrangement similar to that given by 

 Denys for the pigeon. He says that in the injected marrow 

 of frogs the blood corpuscles do not lie free in the marrow, but 

 are contained in definite vessels. Within the lumen of these 

 vessels there are a great number of narrow cells which lie 

 along the walls of the vessels, while the blood corpuscles of 

 the circulating blood pass through the middle. Hayem (31) 

 holds an entirely different view of the origin of the red 

 corpuscles. Hayem, as is well known, deserves the credit of 

 giving the first elaborate description of the blood plates. Al- 

 though these elements had been mentioned, and to a certain 

 extent studied, before his time, Hayem's investigations into 

 their structure and meaning seem to have given the impulse 

 to the great amount of work which has been directed to them 

 within recent years. He attributed to the blood plates the very 

 important function of forming the new red corpuscles. The 

 blood plates, in fact, are in his opinion only young red corpus- 

 cles possessing the shape of the red corpuscles, — biconcave 

 discs, — and in many cases having a greenish tint from the 

 haemoglobin which has begun to form in them. He speaks of 

 the blood plates, therefore, as " haematoblasts." As proof for 

 this view, he states that intermediate forms can be found be- 

 tween the typical blood plate and the ordinary red corpuscles, 

 and these intermediate forms are especially numerous after 

 severe hemorrhages when we should expect a rapid regeneration 

 of new corpuscles. These statements, however, have not met 

 with confirmation from the work of others. Most of those who 

 have studied the blood plates agree in the conclusion that they 

 do not develop into red corpuscles, however much they differ 

 on other points. It is rather interesting that Zimmermann 

 (32), who was one of the first to notice the blood plates, to 

 which he gave the name of "elementary particles," also thought 

 that they develop into red corpuscles. 



Gibson {y^ believes with Lowit that the spleen and the 

 lymph glands as well as the marrow take part in the production 

 of red corpuscles throughout extra-uterine life. To establish 

 the fact that the spleen makes red corpuscles he removed that 

 organ from three dogs. In two of them he was able to demon- 

 strate a slight diminution in the number of red corpuscles, 

 while the effect upon the number of white corpuscles was not 



