234 -DE. W. N. r. WOODLAND ON THE 



for absorption when the blood readies the gas gland. Is there 

 any evidence that the cells of the gas gland absorb this oxy- 

 haBmoglobin dissolved in the blood plasma ? It is not too much 

 to say in reply that every preparation of a gas gland in at all 

 an active condition does provide very substantial evidence as to 

 the actual occurrence of this process. In every such preparation 

 (see figs. 28-31, 50, 68, 73, e. g.) it is at once noticeable that the 

 cytoplasm of the gas gland cells in contact with the capillaries — 

 and usually the cells ai-e only separated from the blood by the 

 thin endothelium — is of dense appearance and forms a perivascular 

 zone quite distinct from the rest of the cell-protoplasm, a feature 

 wdiich has been described and figured by all recent observers of 

 gas gland structure — Jaeger, Bykowski, Nusbaum, Reis and the 

 present writer (see Part I.). ISTusbaum & Reis hold that this 

 appearance of the cytoplasm next the blood vessels is merely evi- 

 dence of absorption from the blood of the nutritious matter afforded 

 by the disintegration of the erythrocytes, but for the reasons just 

 given we prefer to believe that the oxygen associated with the 

 haemoglobin is the desideratum of the gland cells and that what- 

 ever nutritive value ingested fragments of stroma may possess is 

 quite a minor matter. However, the opinion of Nusbaum & 

 Reis is of value in supporting our conclusion that the cells of the 

 gas gland do actually absorb from the blood material liberated by 

 the breaking-up of the erythrocytes. Examination of good 

 preparations of active glands shows that this darkening of the 

 cytoplasm of the individual gas gland cell situated next the blood- 

 channel really possesses a striped appearance (PL IX. fig. 73) — 

 Bykowski & Nusbaum, e. g., describe it as " die charakterische 

 Streifung des Protoplasmas rings um die Blutgefiisse " — similar to 

 that seen at the edges of the cells lining portions of the gut, in 

 the Sertoli cells of the testis and in other cases, and this striping 

 found in so many kinds of cells is proof of a process of absorption 

 taking place. We do not suppose that the fragments of corpuscle 

 substance composing the granular matter in the blood stream ai'e 

 absorbed by the gas gland cells, but only the oxyhsemoglobin 

 dissolved in the plasma, and the fact, which M^e have previously 

 stated, that the veins of the rete mirabile are in active glands full 

 of this granular matter is in accordance with this view. It can 

 thus be proved by what practically amounts to actual demon- 

 stration that the cells of the gas gland do absorb the dissolved 

 oxyhEemoglobin directly from the blood (see Addenda (3)), and the 

 natural inference is that this is employed for the supply of oxygen 

 to the bladder. 



Judging from analogies provided by other classes of secreting 

 cells, what possibly happens in the metabolism of the gas gland 

 cell in the production of bubbles of ox3'gen gas from the absorbed 

 oxyhsemoglobin dissolved in the blood plasma is that a,t that end or 

 pole of the gas gland cell situated next the blood stream the 

 dissolved oxyhpemoglobin forms a loose combination with the 

 cytoplasm, this combination being merely a temporary linkage of 

 the molecules of the two substances (similar, e. g., to the linkage of 



