ROTIFERA. 



399 



reddish colour ; a few others were so trans- 

 parent, that if you held them up between your 

 eye and the light, you might move your fingers 

 behind them, and see the motion through their 

 bodies. 



" After that these animalcula had lain thus 

 dried up a day or two, I invited some gentle- 

 men to come and partake of the agreeable 

 spectacle with me, that is, to see how the said 

 animalcula would divest themselves of their 

 globular figure, and swim about in the water. 

 According to which, after my friends had 

 satisfied their curiosity in viewing the animal- 

 cula in their oval or globular form, some of 

 which were so pellucid as if they had been 

 little glass balls, I poured some water into the 

 glass tube, whereupon they presently sunk to 

 the bottom, and then the gentlemen took the 

 said tube into their hands, and viewing it one 

 after another through a microscope, they saw 

 the animalcula, after the space of about half 

 an hour, beginning to open and extend their 

 bodies, and getting clear of the glass to swim 

 about the water, excepting only two of the 

 largest of them, that stayed longer on the 

 sides of the glass before they stretched out 

 their bodies and swam away." 



Since the period that Leeuwenhoek made 

 these observations, this subject has been one 

 of great interest to naturalists ; and a question 

 has been raised as to the condition of the 

 dried animalcules. Leeuwenhoek seems first 

 to have raised this question, by declaring that 

 complete desiccation must involve the death 

 of an animal, and as it could not come to life 

 after once dead, that the revivified animalcules 

 were not completely desiccated. The experi- 

 ments of Leeuwenhoek were repeated by other 

 observers, and the same results obtained. 

 Needham not only saw it in the Rotifers, but 

 also in the Vibrio of blighted wheat. His opi- 

 nion was, that the desiccation was quite com- 

 plete. Needham's experiments were repeated 

 by Baker, who also came to the same conclu- 

 sion. These observers were followed by 

 Spallanzani, who, in a most elaborate series 

 of investigations, confirmed the conclusions 

 at which Needham and Baker had arrived. 

 He, however, points out the fact, that the re- 

 vivification of the animalt'ules was much more 

 constant when they were dried with sand than 

 when dried on a smooth surface. He found 

 also that animalcules when in this desiccated 

 state would bear a much greater heat, as well as 

 a much more intense degree of cold, than when 

 in an active state. Animalcules that, whilst 

 living, would not bearahigher temperatare than 

 100 Fahr., when dried were resuscitated after 

 having been exposed to a temperature of 144 

 Fahr. They also recovered after being ex- 

 posed to a degree of cold 24 cent, below 

 zero. Although numerous facts of the same 

 kind were recorded by subsequent observers, 

 the accuracy of these observations have been 

 doubted by several eminent naturalists, at the 

 head of whom stands Bory St. Vincent, who, 

 in the article Rotifcrcs, in the Dictionnaire 

 Classique d'Histoire Naturelle, says, that the 

 desiccated animals have not been resuscitated 



at all, but that they are developed from eggs, 

 in the same way as the Daphnia and other 

 minute entomostracous Crustacea are de- 

 veloped after the first shower of rain which 

 falls on the soil in which their ova are con- 

 tained. The correctness of these observations 

 can now hardly be doubted ; and since the 

 time that Bory St. Vincent wrote, a great 

 number of observers of undoubted accuracy, 

 have repeated the experiments of Spallanzani 

 and others, and have arrived at the same con- 

 clusions. Doyere, a French naturalist, pub- 

 lished a very extended series of investigations 

 on this subject, in the Annales des Sciences 

 Naturelles for 1842, in which various species 

 of animalcules were perfectly desiccated and 

 resuscitated under circumstances which would 

 entirely prevent the supposition of a develop- 

 ment such as was suggested by Bory St. 

 Vincent. Experiments of the same kind have 

 been performed by observers in our own 

 country. Dr. Carpenter says, " In the sum- 

 mer of 1835, I placed a drop of water con- 

 taining a dozen specimens of the Rotifer 

 vufgaris on a slip of glass, and allowed the 

 water to dry up, which it did speedily, the 

 weather being hot. On the next day I ex- 

 amined the glass under the microscope, and 

 observed the remains of the animals coiled up 

 into circles ; a form which they not unfre- 

 quently assume when alive, but so perfectly 

 dry that they would have splintered in pieces 

 if touched with the point of a needle, as I 

 had observed before in similar experiments. 

 I covered them with another drop of water, 

 and in a few minutes ten of them had revived, 

 and these speedily began to execute all their 

 regular movements with activity and energy. 

 After they had remained alive for a few hours, 

 I again allowed the water which covered them 

 to dry up, and I reviewed it on the following 

 day with the same result. This process I re- 

 peated six times ; on each occasion one or two 

 of the animals did not recover, but two sur- 

 vived to the last, and with these I should 

 have experimented again had I not acciden- 

 tally lost them." 



Professor Owen in his Lectures, after 

 alluding to the experiments of Professor 

 Schulze on this subject, says, " I myself wit- 

 nessed at Freiburg, in 1838, the revival of an 

 Arc/iscon, which had been preserved in dry 

 sand by the professor upwards of four years.'' 

 We must, however, quote one great authority 

 against the view that a perfect desiccation of 

 the resuscitated animals has ever taken 

 place, and that is Professor Ehrenberg him- 

 self. He does not go so far as Bory St. 

 Vincent, but regards the desiccation spoken 

 of as an assumption, and supposes that the 

 rotiferous and other animalcules which are re- 

 vivified have the power of living in both water 

 and air; although they do not perform their 

 functions so actively in the latter, yet that they 

 still perform them. He says that he has seen 

 the stomachs of Rotifera filled with granules of 

 a conferva which was growing in the sand in 

 which they were supposed to have been desic- 

 cated. Although we feel that the opinions of 



