WITH NOTES ON THE WEST INDIAN SPECIES. 



241 



although in Pt. flava the eosinophile globules occur in great profusion in company with 

 mature ova. 



The mature eggs are wmall, round and subtransparent. They measure '06 mm. in 

 diameter' and, when freshly isolated from the body, are found to be contained in a 

 double-contoured membrane between which and the ovum itself there is an intervening 

 space. The size of the ova in Enteropneusta is particularly noteworthy since it enables 

 us to determine whether any species will develop with or without metamorphosis. 



With regard to the nature of the cells which contain and produce the eosinophile 

 globules I cannot add very much to Spengel's observation.s. Spengel sought in vain for nuclei 

 in these cells in Pt. mitiuta, but left it doubtful whether certain peripheral flattened nuclei 

 belonged to them or not. In PL flava I think I can state definitely that these cells do 

 not contain normal nuclei, for the simple reason that the eosinophile globules themselves are 

 apparently products of nuclear degeneration. The course pursued in tliis process of degene- 

 ration is apparently that of hypertrophy of the nucleolus to which must perhaps be added a 

 multiplication of nucleoli. My interpretation of the appearances presented is that the entire 

 original nucleus undergoes a nucleolar degeneration analogous to fatty degeneration. Spengel 

 points out that these fat-like globules are not fat since they are unaffected by the usual 

 fat-solvents and are also very resistent to caustic potash. He says that sometimes they stain 

 very darkly with haematoxylin and at other times remain quite unstained. This would 

 appear to indicate an ever-changing chemical constitution. Spengel does not seem to have 

 treated them with eosin. In his Taf. XL, Fig. 23 Spengel figures these globules of various 

 graded sizes filling up the cells which contain them. In the text (p. 656) he says, " Bisweilen 

 nimmt eine grossere Kugel die Mitte ein und kleinei^e umgeben sie." What sometimes happens 

 in Pt. minuta, happens as the rule if not invariably, in Pt. flava. 



In this species the normal condition of these nutrient cells at a stage preceding that of 

 their maximum development is shown in PI. XXVIII. Fig. 11. The large central globule 

 is surrounded on all sides by very much smaller, but otherwise similar, globules. Of course 

 at different stages of growth the contrast in size is not so great as shown in the figure, 

 and I am quite unable to say whether the globules increase in size entirely by intus- 

 susception or whether fusion takes place. Spengel could form no opinion as to the relation 

 of these bodies to the sexual elements. As he saw in Pt. minuta and I have seen in female 

 Pt. ruficollis n. sp., tlie globules disappear at the period of complete maturity. But the eggs 

 retain their small size and, as mentioned above, in Pt. flava ripe eggs coexist in tlie ovaries 

 with abundant eosinophile globules. In fact this substance appears to serve two functions. 

 The first function, it would seem necessary to assume, would be the nutrition of the gi'owing 

 germ-cells. The second, which later becomes the principal function, is not that of actively 

 nourishing the germ-cells, but of providing an albuminous medium to preserve the germ- 

 cells under the best possible physiological conditions during the final crucial stages of 

 maturation. 



That these globule-containing cells, in their original quality of nucleated cells, are in a 

 condition of degeneration, is merely a statement of fact. One of the chief reasons which 

 led me to the above interpretation is that the large central globule is often seen to contain 

 clear refringent inclusions, closely resembling, on a larger scale, analogous inclusions whicli 



1 In my former paper, b\' a lapsus calami, the diameter was stated to be "00(5 mm. although the correct 

 magnification was given in the explanation of the plate. 



34—2 



