614 DE. H. CHABLTON BASTIAN ON THE ANATOMY AND PHYSIOLOGY 



during the interval ; much in the same way as the length of time that seeds are capable 

 of retaining their power of germination, is greatly influenced by the method of their 

 preservation — by variations in their hygrometrical condition, and degree of exposure to 

 the air. 



It was first observed by Spallanzani that one of the essential conditions for the revival 

 of the Rotifers and Anguillules found in tufts of moss was, that their period of desiccation 

 should either be passed in these tufts, or else that during the same time their bodies 

 should be more or less covered with sand*. His explanation of this fact was that the 

 access of air exercised a prejudicial influence upon the delicate structures of these animals. 

 The fact is quite in accordance with my own observations, and as regards its explanation, 

 I am able to offer nothing more satisfactory than that advanced by Spallanzani. He 

 alternately dried and moistened the same animalcules twelve times with similar results, 

 except that the number of the revivers was successively smaller each time, but aftet 

 the sixteenth moistening he failed to restore any of them to lifef . 



Since Spallanzani's time the most interesting experiments concerning the power of 

 reviviscence in the Anguillulidce have been made by M. Davaixe J and by MM. Doybhk 

 and Gavaeeet§. I shall briefly notice some of the principal results arrived at by these 

 experimenters before detailing my own observations on this subject. 



Davaine ascertained that the time of saturation in water necessary for the recovery of 

 the young of Tylenchus tritici, was not directly proportional either to the length of their 

 period of desiccation, or even to the actual degree of desiccation to which they had been 

 submitted. With regard to the length of the period of desiccation he adds, "il y a, 

 sous ce rapport, moins de difference entre les larves d'un an et celles de quatre ansj 

 qu'entre les lars^es d'un mois et celles d'un an." To ascertain the influence of the -degree 

 of desiccation upon the time necessary for their recovery he made the following expe- 

 riments. LarviB three years old were taken, and placed under the receiver of an air-pump, 

 together with a large capsule containing concentrated sulphuric acid to absorb all 

 aqueous vapour ; the air was then exhausted as completely as possible, and the animals 

 allowed to remain in vacuo for five days. Then when withdra^Ti and immersed in pure 

 water, most of them resumed their activity and vital manifestations after a period . of 

 three hours. Subsequent experiments convinced him that larvae, varying from one to 

 three years old, invariably recovered as quickly after they had been completely desiccated 

 by a sojourn of four days in a vacuum, as did others of the same age that had merely 

 been exposed to the air for a similar period. In grains which have been gathered only 

 a few days the animals may be revived in less than an hour ; in those which have been 

 kept four years in not less than ten, fifteen, or twenty hours. It is quite improbable, 

 however, that these last could be so dry as fresh grains which had been preserved in a 



* Tracts on the Kat. Hist, of Anim. and Veget. Transl. by Dalxeix, vol. ii. (ed. 2) p. 129 tt seq. 



t OwEx's Lect. on Comp. Anat. 2nd ed. p. 54. 



X Eceherclics sur rAngiiillulc du ble nielle, 1859, pp. 39-61. ; 



§ Ann. dcs Sc. IS'at. 4'^« scr. t. si. 1859, p. 319. 



