180 GENERAL HISTORY OF THE INFUSORIA. 



" ^We have seen,' they say, ' that these resting- cells, after they have been 

 formed by the metamorphosis of a motile primordial cell, increase in gTO"\vth 

 considerably, that they go through a further vegetatiye development, and 

 have, therefore, not reached the termination of their vital process.' And 

 they then add — ' It is contrary to the idea of a sj^ore, that it should continue 

 to grow after having assumed the character of a resting-cell ; and the fact has 

 never yet been observed in any single case.' It would seem that these 

 remarks are intended to be limited to the Algae ; but it is worthy of obsei-va- 

 tion, that the spores of the ascigerous Fungi frequently increase in gro^i;h 

 after escaping from the asci ; and if this circumstance is not to be looked upon 

 as affecting their character as spores, it is difficult to see why a different rule 

 should be applied to the Algae. 



" Cohn and Wichui'a moreover consider that the increase by self- division 

 is irreconcileable with the idea of a spore. In speaking of the red cells of Chla- 

 mydococcus pluvialis, they express a doubt whether in those cells increase by 

 self-division takes place, but assert that, if such should prove to be the case, 

 it would be conclusive against their being spores, considering self-division (if 

 I understand them right) to be a process of vegetative development distinct 

 from germination. These observations are worthy of the careful attention of 

 microscopists ; and without ventming an opinion as to their correctness, I 

 would only remark, that if the resting-cells of Chlamydococcus and Stejpha- 

 nosphcera are not to be considered spores, that character must also be denied 

 to the resting-cells of (Edocjonium, BidhocJicete, Draparnaldia, Spli(xroplea, 

 and Volvox, if, as is more than probable, there should be detected in these 

 latter cells, 1st, an increase in growth after becoming quiescent ; or, 2dly, 

 increase by seK- division." 



YoLvox (XX. 32-49). — This genus lias always been an especial favour- 

 ite -^ith microscopical students. Its colonies of numerous monadiform green 

 bodies distributed over the surface of miniatui'e globes, endowed with active 

 motion, revolving hither and thither, form one of the most pleasing objects 

 that the microscope can display. Moreover, the more minutely the globes of 

 the Volvox are exammed, the more interest do they awaken, by reason of the 

 regularity and beauty of their intimate structure, and of the results of their 

 \-ital processes. 



The consequence of this has been a host of observers and writers on the 

 anatomy and physiology of Volvox, and a formidable array of conflicting 

 views on those topics, the consequence of careless and insufficient research, 

 of indifferent instruments, and of the influence of fanciful hypotheses. We 

 shall, however, attempt no analysLs of the many accoimts of Volvox in 

 existence, but restrict ourselves to an abstract of the more recent important 

 observations and conclusions of Professors Williamson and Busk, particularly 

 of the former and earher observer on that org^anism, premising it by a brief 

 notice of Ehrenberg's views. 



Formerly the whole globular mass was regarded as a single warty and 

 ciliated animalcule ; and the act of bursting, whereby the smaller globes de- 

 veloped within it which had reached maturity were liberated, was considered 

 to be the birth of young animals. This theory Ehrenberg clearly proved to 

 be erroneous, and showed that, to iLse liis language, the supposed spherical 

 animalcule was in reality a colony of monad-like beings distributed over the 

 inner surface of a common lorica, and connected together by fihform cords or 

 tubes ; in other words, he proved each sphere or globe to be, if we may so 

 term it, a hoUow cluster of many hundi^eds or even thousands of h\-ing occu- 

 pants, and to frequently contain within it other smaller hoUow spheres, 

 similar in nature to itself, and in fact developed from it by a process of self- 



