630 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Classification of Sponges.* — Prof. W. J. Sollas gives the following 

 classification of the phylum Porifera : — 

 Class I. Plothospongioo. 



Sub-class 1. Ilexactincllida. 



Order 1. Lyssakina. 

 Order 2. Dictyonina, 

 Sub-class 2. Dcmospongia?. 

 Tribe a. Monaxida. 



Order 1. Monaxona. 

 Order 2. Ceratosa. 

 Tribe b. Tetractinellida. 



Order 1. Choristida. 

 Order 2. Lithistida. 

 Sub-class 3. MyxospongiaB. 



Order 1. Halisarcosa. 

 Order 2. Chondrosiosa. 

 Class II. Calcispongiro. 



Protozoa. 



Physiology and Biology of Protozoa.f — Dr. A. Gruber gives an 

 account of his observations on artificial divisibility and regeneration 

 in Protozoa. He has chiefly made use of the large Stentor cseruleus ; 

 here, as in Oxytricha, the anterior end replaces the lost posterior end, 

 and the right side the lost left side, and vice versa. He finds that the 

 regeneration of the organula follows the same course as their new 

 formation in spontaneous fission. The unknown impulse which 

 induces the animals to divide, and the irritation caused by the violent 

 removal of a part of the body, are identical in their effects. If we 

 ascribe regeneration in the Metazoa to the influence of embryonally 

 formed cells, we must in the Protozoa ascribe the function of 

 new formative elements to originally formed elementary particles 

 ("micellse") which are subject to the directing influence of tbe 

 nucleus. Regeneration is due only to a conversion of elementary 

 parts already present, and is set up by external irritation ; it takes 

 place rapidly, and in the Stentor is very powerful ; no particular part 

 of the body appears to be specially disposed thereto, but all parts react 

 in tbe same way. 



The author relates experiments which justify these conclusions, 

 and next describes others which show that two artificially produced 

 halves are able to increase spontaneously at exactly the same time, 

 although after section they were apparently not equivalent ; thus, 

 in one case, the anterior portion which still possessed the peristomial 

 area, mouth, and oesophagus had only to go through the process of 

 wound-healing, while the posterior portion had to produce all the 

 organs anew; the latter was, nevertheless, able to answer to the 

 impulse just as quickly as the former. This observation shows also 

 that the material for new formations in the Infusoria is not stored 



* Scientif. Proc. R. Dublin Soc, v. (1885; p. 112. 



t Ber. Naturf. Ges. zu Freiburg i. B., i. (1886) Heft 2 ; translated Ann. and 

 Mag. Nat, Hist., xvii. (1886) pp. 473-94. 



