270 Mr. J. T. Arlidge on some of the Phases of Development 



croscope, and possessed in its interior several globules about a 

 clear nucleus, indicating an aptness for ulterior changes, I deter- 

 mined to prosecute a further observation of it. 



Occupying about the centre of the being was a distinct, clear 

 nucleus*, and around this were arranged six or seven granular 

 greenish globules, with interspersed particles or granules. The 

 circumference was also furnished with a single row of long and 

 large cilia, which caused the animalcule to rotate on its own axis, 

 without altering its relative position (PL VII. B. fig. 1). 



After observation had been continued a little while, most pro- 

 bably from a change of position of the creature, an interior, con- 

 tained circle came into view, eccentric to the outer one so far, 

 that an interval was left between the two for about half of their 

 periphery, whilst in the remaining half the two spheres were in 

 apposition. This interval left between the two had a rather 

 darker colouring, owing to its finely granular character, being 

 minutely dotted as in engraving (fig. 2). 



These appearances were present about half-past one o'clock p.m. 

 Moreover, at the same time that the two circles came under no- 

 tice, the inner one was observed to rotate independently of the 

 outer one, and indeed in the contrary direction, — a result I believe 

 due (judging however from some slight indications only) to its 

 surface being clothed with delicate cilia. Thus, the cilia of the 

 external tunic bent themselves to the leftf, producing a motion 

 from right to left, whilst the inner one revolved turning from 

 left to right. This contrariety in the direction of the revolution 

 of the two spheres was very observable, being, at this period and 

 for some time afterwards, very active. 



In process of time the motion of the contained circle waxed 

 more rapid than that of the external, and seemed to impede the 

 latter; at least, the rotation of the outer sphere became irre- 

 gular, and was altogether slower than when first witnessed. 



Between two and three o'clock the number of included glo- 

 bules had decreased ; and instead of six or seven about the pellucid 

 nucleus, only four could be discovered, but these were of larger 

 size than those heretofore noticed. One of the four seemed more 

 granular than the rest, and deeper seated ; another, of the largest 

 size, had one-half of its cavity clear, the other occupied with 

 green granular matter. The remaining two were tolerably clear. 

 Scattered in the interspace between the vesicles were some 

 rounded granular green masses about one-fourth the size of the 

 former, and, in addition, the common formless green particles 

 (fig. 3). 



* This nucleus would, according to Ehrenberg's ideas, be called the testis 

 or sperm-cell. 



f I speak here of the apparent directions assumed, viewed under the mi- 

 croscope : hence the real directions are jflst the reverse. 



