488 SUMMARY OK CURRENT RESEARCHES RELATING TO 



wall of the gemmule by amoeboid " phorocytes." The aggregates of 

 gemmules in the body of the sponge sometimes have some foreign 

 concretion in their interior, and sometimes have no nucleus at all. 



Pectispongilla.* — Nelson Annandale redefines this genus of fresh- 

 water sponges. It includes small Spongillinae of massive or encrust- 

 ing habit, of soft and friable consistency, with delicate skeletons in 

 which vertical fibres, though well-defined and not devoid of horny 

 substance, are always very slender. Dermal membrane aspiculous ; 

 skeleton-spicules rough or smooth amphioxi ; free microscleres present 

 in the flesh of the sponge, often of more than one type ; gemmule- 

 spicules with the extremities flattened and expanded in the main axis, 

 the terminal expansions bearing, on one face only, large spines arranged 

 longitudinally in parallel comb-like rows. The type species is Pecti- 

 spongilla aurea Annandale. Two others are described. The geographical 

 distribution is in the plains of Travancore and Cochin, in the southern 

 part of the Malabar zone of Peninsular India— a limited range. The 

 genus is probably derivable from a little group of species of Spongilla, 

 in the sub-genus Euspongilla, typified by S. crater if or mi* Potts. 



Protozoa. 



Reproduction of Hypotrichous Infusorians.f— Gr. A. Baitsell has 

 studied the so-called life-cycle in Oxytricha fallax and Pleurotricha 

 lanceolata, which were cultivated in a " constant " medium consisting 

 of a 0-025 p.c. solution of Liebig's extract of meat, a hay-infusion 

 medium, and a "varied environment" medium. The cultures were 

 kept under observation for many months, in one case for nearly two 

 years. At the beginning in each case the animals gave evidence of 

 "being thoroughly normal, but previous to the dying out of a culture 

 there was an appearance of atypical and degenerate individuals, similar 

 to those found by former investigators, and interpreted by them as due 

 to an inherent condition of senescence. The experiments indicate, 

 however, that the dying out of some of the culture was due, not to a 

 condition of inherent senescence, but to the fact that the culture con- 

 ditions supplied were not entirely favourable to the indefinite existence 

 of the organisms bred under observation. In Oxytricha fallax " sister 

 cells " bred in a mass-test-tube culture lived more than twice as long 

 as those bred in daily isolation cultures. In the case of Pleurotricha, 

 culture conditions have been found (in a hay-infusion medium) in which 

 this organism will apparently live indefinitely without conjugation or 

 artificial stimulation. 



Architecture of Foraminifer Shells. % — E. Heron-Allen directs 

 attention to the purposiveness and beauty of some of the shells made 

 by Foraminifera. Some forms, such as Hwplophragmium agglutinans, 

 incorporate into their shells fragments of heavy gem minerals, such 



* Records Indian Mus., xi. (1915) pp. 171-8 (5 figs.), 

 t Journ. Exper. Zool., xvi. (1914) pp. 210-34 (1 pi.). 

 X Ex. Reports Royal Institution May 21, 1915, pp. 1-13. 



