L90 SUMMABY OF CURRENT RESEARCHES RELATING TO 



of a continuous shoot of collar-colls, suspended evenly in tlio midst of 

 the dermal layer, which formed a trabecular system, developed as much 

 towards the interior as towards the exterior of the gastral layer. The 

 spicular skeleton arose first in the trabecular system, situated exter- 

 nally to the gastral layer, and the earliest regular form of spicule was the 

 stauractinc. This stage of evolution is represented by the palaeozoic 

 Stanractinophora of Sehrammen, especially by the Protospongidaj. The 

 next step in phylogeny was the folding of the gastral layer to form 

 distinct flagellated chambers, and with this change the stauractines 

 developed additional rays directed radially, thus producing the hexactines 

 found in all Hexactinellida after the palaeozoic epoch, and probably also 

 in many oven at that early time. 



Genus Raspailia.* — F. K. Pick gives a monographic account of this 

 genus of horny sponges belonging to the family Ectyoninre. He dis- 

 cusses the history of the genus, gives a systematic account of the species, 

 adding to the list, and describes the structure of the canal-system, skele- 

 ton, and so forth. 



Studies on the Hexactinellida.f — Isao Ijima makes a fourth con- 

 tribution of hexactinellid studies, and deals with the family Rossellidre. 

 He re-defines the family, gives a key to the genera, and treats of about 

 thirty species, five of which are described for the first time. The twenty- 

 three plates are of great excellence. 



Protozoa. 



Movement and Reactions of Amceba3.:|:— H. S. Jennings has found 

 it possible to determine the exact movements of the outer layer of 

 Amoeba verrucosa, and others, by causing foreign particles to adhere to 

 the surface. The movements of these particles show that the motion of 

 an amoeba is of a rolling character, as Lachmann pointed out in 185S, and 

 Wallich in 1863. A single particle was seen to complete the circuit of 

 the cell many times. It is not merely a thin outer layer that moves 

 forward ; on the contrary, the whole substance of the amceba, save that 

 part which is in contact with the substratum, flows forward in a single 

 stream. There is typically no backward current in a progressing 

 amoeba. In a free pseudopodium all parts move outward, new portions 

 of the surface of the body continually passing to the surface of the 

 pseudopodium. Thus the movements of amoeba? lose their supposed 

 resemblance to those of a fluid mass moving as a result of a local change 

 in surface tension. The actual movements of an amoeba resemble even 

 in details the movements of a drop of fluid which adheres on only one 

 side of the substratum. Purely physical explanations will not work : 

 still loss, when we consider cases of an amceba pursuing a spherical cyst 

 of Euglena for fifteen minutes. One amoeba pursued another for a long 

 time, finally capturing and ingesting it. After being carried for a short 

 distance, the prey partly escaped and was recaptured. It again escaped 



* Arch. f. Naturges., lxxi. (1904) pp. 1-48 (4 pis.). 



t Journ. Coll. Sci. Univ. Tokyo, xviii. (1904) pp. l-o07 (23 pis. and 10 figs.). 

 X Biol. Centralbl., xxv. (1905) pp. 92-5 (2 figs.). Publication No. 16, Carnesrie- 

 Inst. "Washington (1904) pp. 129-234. 



