466 SUMMARY OF CURRENT RESEARCHES RELATING TO 



two parts, and both regenerated completely, although with constant dimi- 

 nution in bulk. Increase by fission was entirely stopped, but the power 

 of regeneration remained. 



" In regeneration, under the circumstances of these experiments, two 

 processes are taking place side by side ; not only is new tissue being 

 formed at the cut end, but the old tissues are undergoing a translocation 

 and partial re-differentiation, to accommodate tbemselves to the new pro- 

 portion that must be assumed. The new tissue at the cut end must be 

 formed entirely from the old tissue, and the final result involves, there- 

 fore, an extensive working over of the old material. The original tissues, 

 with constant losses, owing to destructive metabolism, are moulded into 

 the form of a new individual. . . Not less remarkable is the maintenance 

 of form in individuals that gradually waste away to one-hundredth part 

 or less of their original bulk, but remain active and normal, without 

 hint of sickness." 



New Planarian.* — Mr. W. C. Curtis has obtained in a stream near 

 Williamstown, Mass., a Planarian which is apparently new, and which 

 is of interest on account of the extreme simplicity of the reproductive 

 system. The follicles of the testes are unusually few in number (aver- 

 age about 9), and are not paired except in the head region. Testicular 

 canals, seminal vesicles, and penis, all show great simplicity of structure. 

 The ovaries are not compact, but consist of straggling lobes, and show 

 little differentiation from the yolk-glands and oviducts. The uterus is a 

 slightly curved tube of uniform diameter without terminal enlargement ; 

 there are no accessory glands other than the shell gland of the vagina. 

 The new species has been named Planaria simplicissima. 



Cestode Nervous System.f — Mr. W. L. Tower has applied Golgi's 

 method, the methylen-blue method, and Von Bath's method, to the study 

 of the nervous system of Moniezia expansa. The best results were ob- 

 tained with Von Eath's fluid followed by crude pyroligneous acid, and the 

 want of success with the other methods, notably the methylen-blue, was 

 due in part to the difficulty of finding a suitable medium in which to 

 keep the worms during transport to the laboratory. Later it was found 

 that any fluid containing sodium chloride is injurious, but the worms 

 can be kept alive without injury for several days in a nutrient fluid if 

 this salt be absent, thus affording opportunity for the use of methylen- 

 blue. The material was obtained from the small intestine of Ovis aries, 

 and no difficulty was experienced in obtaining an abundant supply. 



The nervous system was found to be devoid of any continuous pro- 

 tective investment, but the more important nerve-trunks display scattered 

 cells with branching processes, the " binding-cells " of the author, 

 doubtfully homologous with the Hullzellen described by Zernecke for 

 Ligula. In the scolex the nerve apparatus has the following parts : — 

 (1) an anterior nerve-ring with four ganglia ; (2) a pair of large cephalic 

 ganglia ; (3) connecting nerves between the preceding ; (4) dorsal or 

 ventral commissures connecting the outer ends of the cephalic ganglia. 

 These structures are described in some detail. In the neck region there 

 are six distinct longitudinal trunks, a large lateral one at either side, two 



* Zool. Jahrb. (Abt. Anat.), xiii. (1900) pp. 447-66 (2 pis.), 

 t Tom. cit, pp. 359-84 (5 pis.). 



