G4 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Spongilla fragilis from at least thirty-two localities in oighteen North 

 American States, S. Jacustris from twenty-six localities in sixteen States, 

 and Meyenia fluviatilis from twenty-five localities in fourteen States. 

 Hardly any two specimens are exactly alike in their so-called typical 

 features, hut all may be grouped, and common definitions or descriptions 

 will, without undue elasticity, cover them all. 



A diagnosis of the European Spongillida?, translated from the 

 Bohemian text of Prof. Vejdovsky, follows, and this is succeeded by a 

 synopsis of Mr. Carter's classification. Then comes a key to the species 

 of Spongilla, and descriptions of the species, those that are American 

 being treated with more detail than the rest. The genera Meyenia, 

 Heteromeyenia, Tubella, Parmula, Carterius, Uruguaya, Potamolepis, and 

 Luhomirshia (?) are treated in the same way, so that a valuable com- 

 pendium is produced. 



In conclusion the author says, " Some points .... worthy of tho 

 thought and study of future students have already been suggested, such 

 as the necessity of gemmules in fresh water as distinguished from marine 

 sponges ; the process of their formation ; their functions, and the means 

 by which that end is attained; the law of variation in the quantity and 

 character of the enveloping crust; and the time and mode of formation 

 of the imbedded armature — all have yet to be conclusively studied. 

 Other questions of a more limited character occur in the search for the 

 line of derivation that must be supposed to run through all the genera 

 and species ; and in the association, apparently indicated amongst other- 

 wise dissimilar species, by the presence in them of correspondent forms, 

 such as the birotulate dermals found in certain Spongillse and Meyenise, 

 and the more frequent recurrence in several genera of acerate dermals 

 with characteristic, centrally located, perpendicular spines, &c." 



Development of Generative Products in Spongilla.* — Herr K. 

 Fiedler argues, against Prof. Goette, the unicellularity of the ovum of 

 Spongilla. He has always found distinct cell-boundaries in the egg-cell, 

 and only one nucleus. Double coloration with picrocarmine and " bleu 

 de Lyon," with quick washing of the sections with slightly ammoniacal 

 alcohol, gives a bright red colour to the nucleus, and colours blue even 

 the smallest parts of the yolk. The author finds that the large round 

 vitelline spheres do not, as Goette imagines, appear first, but that they 

 are preceded by all possible stages of smaller yolk elements. The folli- 

 cular cells are regarded as parenchymatous cells which have been 

 flattened out by the pressure of the growing egg. Some of them appear 

 to be special nutrient cells, and often their amoeboid processes may be 

 seen pushing themselves between the ordinary follicular cells towards the 

 egg, without, however, fusing with it. They prepare in their interior 

 material which is to be regarded as preparatory to yolk-stuff, and which 

 is given up to the egg by diffusion. 



In addition to these, there are certain amoeboid wandering cells of 

 another kind, the body of which is quite regularly filled by rather large 

 particles. They correspond to those described in the Calcarea by 

 Polejaeff. They are scattered through the whole body of the sponge, but 

 are especially numerous below and among the cells of the cortex, and 

 more particularly near the afferent orifices. They have probably a 

 nutrient function. 



* Zool. Anzeig., x. (1887) pp. 631-6. 



