16 M. E. Claparede on the Circulation of the Blood 



III.— On the Circulation of the Blood in the Spiders of the Genus 

 Lycosa. By Edouard Claparede*. 



The circulation of the blood in the Arachnida has already been 

 the subject of profound investigations. Those of Newport on the 

 circulatory organs of the Scorpion f in particular enjoy a credit 

 to which they are entitled in the highest degree. They have 

 been completed and at the same time corrected in some points 

 of detail by Blanchard. The latter has also bestowed on science 

 some splendid investigations of the circulatory organs of other 

 sections of the Arachnida. He has in particular devoted a con- 

 siderable part of his Memoirs to a Spider of the genus Mygale. 

 At this moment he is publishing some magnificent plates of the 

 anatomy of the Arachnida % ; and although the text relating to 

 the Spiders has not yet appeared, it is easy to see, from the 

 plates already published, the results at which he has arrived. 



It will be seen that on more than one point I cannot agree 

 with M. Blanchard ; but none the less do I accord my tribute 

 of admiration to the labours of that learned anatomist, and this 

 without any reservation. M. Blanchard has resorted to the me- 

 thod of injection already practised by Duges, Newport, and 

 others. I believe that he has obtained from it everything that 

 it can be made to furnish. By its means he has recognized with 

 perfect accuracy all the principal vascular trunks ; but never- 

 theless this method has not always informed him with perfect 

 certainty of the direction of the circulation of the blood in the 

 vessels. Moreover it has frequently spread for him a snare, in 

 which so many anatomists have allowed themselves to be taken 

 under other circumstances. M. Blanchard has too often thought 

 that he found sanguiferous networks, when he had under his 

 eyes only the meshes of an artificial net hollowed out by the in- 

 jected material in the delicate tissues. Once more he has shown 

 how necessary it is that the method of injections should be sub- 

 mitted to a severe check, if we would not reproduce the exag- 

 gerated discredit into which it has fallen in the eyes of more 

 anatomists than one. 



I have followed quite a different course. I have endeavoured 

 to procure young Spiders so transparent as to allow the course 

 of the blood to be investigated in its full activity. The most 

 favourable object that I have hitherto met with is the Lycosa 

 saccata, Hahn. The females of this species carry their ovigerous 

 sac applied to the posterior part of their abdomen. The young 



* Translated by W. S. Dallas, F.L.S., from the 'Annates des Sciences 

 Naturelles,' Nov. 1864, p. 259. 



f Phil. Trans. 1843, part 2, p. 213. 



X L' Organisation du Regne Animal, par Emile Blanchard : Arachnides, 

 livr. 1-16. 



