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V. — On a presumed phase of Actinophryan Life. 

 By J. G. Tatem. 



Plate XV. (Upper part). 



AcTiNOPHHYS SOL is SO often seen in the conjugated condition, and 

 the progress of coalescence between two or more individuals so fre- 

 quently watched, that I need not refer to the mode of its accomphsh- 

 ment. Nor is it necessary that I should remind the reader that much 

 difference of opinion formerly existed as to the nature of the process ; 

 authorities having been equally divided on the subject, some regarding 

 it as a Keproductive — a copulative act, others contending that it is 

 due to accidental contact and partial fission only. Later observers 

 have, however, determined the question by demonstrating the form- 

 ation and expulsion of swarms of " embryonic germs " as the con- 

 sequence of the union.* Whether or not these germs, so copiously 

 diffused into the surrounding water, can ever be kept under obser- 

 vation, or be artificially maintained in the conditions favourable to 

 and for the leugth of time necessary for their development, from 

 embryo to maturity, and that, too, through many possible muta- 

 tions of form, is altogether problematical. But may we not hope 

 that, among the multitude of minute and scarcely -recognized 

 monadiform beings, one or more may be detected which we may 

 reasonably connect with the Adinopliryan germ in its progress 

 towards adolescence. I think so ; and to one such I would wish 

 to draw your attention. 



In water in which the Actinophrys sol is more or less abun- 

 dant, especially in the later months of autumn, certain minute 

 organisms about toVo" to -^^q- ai'e usually found. They are 

 mostly of oblong but inconstant form, transparent, containing a 

 few rather large granules having a greenish refraction, and armed 

 posteriorly with soft-looking spines (pseudopoda), variable in length 

 and number in individuals, and in the same individual also, from 

 time to time (Plate XV., upper part. Figs. 1-3). Their motion is 

 that forward oscillatory one which is effected by the vibrations of a 

 single fine anterior filament, and is moderately quick, occasionally 

 almost rapid. This may be long continued, but patient observation 

 will show that, after some uncertain, wayward movements, they will 

 gradually settle down, flatten out circularly, throw out pseudopoda, 

 sometimes twice the diameter of the disk, and become in all respects 

 perfect Adinoplirya sol (Fig. 4). In this stage the true Actino- 

 phryan voracity is disj)layed. Astasia margaritifera abounded in 



* Vide Mr. Waller's paper in ' Journal of Qnekett Club,' vol. ii., p. 93 ; and 

 President's couimunication to Reading Microscopical Society, reported in 'Mon. 

 Micr. Jour.,' vol. iv., p. 33i. 



