ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1)31 



"tabulate corals" or Polyzoa (some of the • Monticuliporas). There is 

 no dermal epithelium, and the canal system is hymenopylous. 



The author replies to objections (of an a priori character) that have 

 been brought against the sponge nature of Merlin.. He has examined 

 over 500 specimens, and his conviction is that it is a sponge that forms 

 both a siliceous and a calcareous skeleton. 



New Lithonine Sponge from Christmas Island.* — R. Kirkpatrick 

 describes Plectroninia deansii sp. n., found as a thin vitreous-white crust 

 on some pieces of rock dredged off Christmas Island. The skeleton is 

 constructed of fused four-rayed spicules, as in other Lithonine ; the 

 distinguishing feature of P. deansii lies in the character of the loose 

 spicules. These are mostly monaxons, curved at one extremity, running 

 to a sharp point at one end and rounded at the other. One spicule 

 appears to be bifurcated at one end, and may be regarded as a three- 

 rayed form. Kirkpatrick suggests a revised classification of the Phare- 

 tronidae, which he divides into four sub-families : Dialytina3,Pharetroninae, 

 Lithoninas, and Murrayoninse. 



Pharetronid Sponges of Essen Greensand.j — 0. A. Welter gives an 

 account of a collection of the fossil Calcarea from the Essen Greensand. 

 The family Lithonina is represented by eleven species of Porosphserella ; 

 the family Pharetronina is represented by a score of species belonging to 

 the genera Corynella, Peronidella, Steinmannella, etc. The Pharetronids 

 mostly disappeared at the end of the Cretaceous period, and it is uncertain 

 whether they have left any extant descendants. The author indicates his 

 belief that Astroclera willeyana Lister is one of these. 



Protozoa. 



Studies on Pelomyxa.J — Antonin Stole enquires into the membrane 

 around the refractive bodies in the cytoplasm of this giant amoeba. It 

 consists of a carbohydrate more difficult to dissolve than glycogen. He 

 believes that the agglutinin of the refractive bodies forms this protective 

 membrane out of glycogen. When the animal has to fast, a lysin from 

 the refractive bodies dissolves the membrane. Then there is a rnass- 

 agglntination of exhausted refractive bodies ; but, in point of fact, the 

 membrane, is continually being dissolved and replaced. In the same way 

 a nuclear agglutinin makes a nuclear membrane. The symbiotic bacteria 

 of Pelomyxa are agglutinated on the surface of the nucleus and on the 

 surface of the refractive bodies, and sometimes in the cytoplasm in general. 

 There is a bacterio-agglutinin and a bacterio-lysin in continual operation, 

 according to the author, and the capacity that higher animals have of 

 producing immunizing substances (agglutinin, lysin, etc.) has its phy ln- 

 genetic beginning in cases like Pelomyxa. 



Encystation in Pelomyxa. § — A. Stole has studied the encysted stage 

 in this giant amoeba, and finds that it is closely comparable to that in 



* Ann. Nat. Hist., viii. (1911) pp. 177 9 (10 figs.). 



t Yerh. Nat. Yer. preuss. Rheinl., Ixvii. ( 1911) pp. 1-82 (3 pis. and 10 figs.). 



X SB. Bohm. Ges. Wiss. (1910) No. 9. pp. 1-8 



§ SB. Bohm. Ges. Wiss. (1910) No. 1G, pp. 1-7 (1 pi.). 



