416 E. p. CHURCHILL, JR. 



been kept in albumin solutions thus stained are represented 

 in figures 17 and 18. Figure 19 is a i epresentation of the gill 

 filaments of a mussel which had remained in water in which 

 haematoxylin had been dissolved. The granules in the latter 

 will be seen to be much less numerous than in the former and 

 none can be observed clinging to the outer ends of the cells or 

 to the cilia. 



Finally a fact was discovered that led to more definite results. 

 Cowdry, in a paper on mitochondria, makes mention of the fact 

 that he has found that Janus green will, in the living cell, stain 

 lecithin and albumin, the latter more heavily. As mentioned 

 above the author had found that in fixed preparations Janus 

 green stained the entire cytoplasm. An attempt was now made 

 to determine whether or not Janus green might be employed 

 as a means of detecting albumin that might have been absorbed 

 by the cells of the gills or other parts of the outer body walls 

 of the mussels. 



Mussels were put into solutions made up 5000 cc. of water 

 and 100 cc. of albumin stained with Janus green. Control in- 

 dividuals were placed in water in which Janus green had been 

 dissolved. The mouths of these mussels were left open. The 

 experiments were continued for eight days. At the expiration 

 of that period the mussels were killed and their t'ssues were 

 hardened in 10 per cent formalin for a few hours. As albumin 

 is precipitated by formalin, this procedure would cause the pre- 

 cipitation of the albumin in any of the solution which had adhered 

 to the outer surfaces of the cells in addition to the coagulation 

 of what albumin might have been absorbed. In this way ag- 

 gregates of albumin sufficiently large to be visible under the 

 microscope would be formed and thus render it possible to trace 

 this protein histologically. Sections were then cut by the 

 freezing method and mounted in glycerin. The gill filaments of 

 a mussel that had been in the stained solution are represented in 

 figure 20. Numerous green granules of various sizes were found 

 within the cells and within corpuscles in the blood vessels in 

 the center of the filaments. The granules which had taken the 

 stain are represented in the drawing by heavy black dots. In 



