272 QUARTERLY CHRONICLE. 



of the former. The Microzymata are normally simply minute 

 spherical bodies. In this state they exist normally in the 

 human body. But when the tissues are exposed to the air 

 they grow into chains and become Bacteria. MM. Bechamp 

 and Estor seem to think it a proof of these Bacteria being 

 normal c(mstituents of the body, that they are found in the 

 liver. But after all, what is to prevent any organic germs 

 from reaching the inmost centre of the liver, through the 

 mouth, stomach, and gall-duct? 



July. — " On the Existence of Capillary Arterial Vessels in 

 Insects. By Jules Kiinckel.* — Zoologists supposed that the 

 circulation of the blood in insects was limited to certain cur- 

 rents detected by Cams in transparent larvse, when in 1847 

 M. Blan chard proved that the tracheae of these animals ful- 

 filled the function of arteries, by conveying, in a peripheral 

 space, the nutritive fluids to all the organs. He ascertained, 

 by means of delicate injections, the existence of a free space 

 between the two membranes composing the tracheae : the 

 injected fluid expelled the blood and replaced it. 



After having verified and confirmed M. Blanchard's dis- 

 covery, M. Agassiz insisted upon the evidence of the demon- 

 stration. Seeking afterwards to complete this discovery, he 

 paid particular attention to the termination of the tracheae. 

 In a memoir published in I849,t this naturalist distinguished 

 the ordinary tracheae terminating in little ampullae, and the 

 tracheae terminated by little tubes destitute of a spiral fila- 

 ment, which he named the capillaries of the trachea. M. 

 Agassiz expresses himself as folloAvs : — " In the grasshoppers 

 which I injected by the dorsal vessel I found in the legs the 

 muscles elegantly covered with dendritic tufts of these ves- 

 sels (the capillaries of the tracheae) all injected Avith coloured 

 matter ; and in a portion of a muscle of the leg of an Acri- 

 dium fiavovittatum, submitted to a high magnifying power, I 

 observed the distribution of these little vessels, which has a 

 striking resemblance to the distribution of the blood-vessels 

 in the bodies of the higher animals." 



Nearly twenty years have passed since the period Avhcn 

 M. Agassiz announced these facts, which appear to have been 

 but little understood ; for the authors who have written on 

 the anatomy and physiology of insects have not even men- 

 tioned them. 



The direct observation of the ]->henomenon of circulation 

 was wanting j no one had succeeded in detecting the move- 



* Ti-aiisla(r.d in ilic 'Ann. and Mag. Nat. Hist.,' Sept., ISGS. 

 t 'Proo. Aniericaii Association,' 1819, pp. IJO— 143; tiaiiblatcil in 

 'Ann. (les Sci. Nat.,' 3*^ ser., xv, pp. 358— 3()2. 



