274 QUARTERLY CHRONICLE. 



canal; the outer coat, or peritracheal membrane (^peritoneal 

 membrane of the Germans), surrounds the former enve- 

 lope, leavmg an interval, the peritracheal space. But at the 

 point where the tracheae jienetrate between the muscular 

 fibres, the inner coat disappears, and the aeriferous canal 

 terminates csecally, whilst the outer coat or peritracheal 

 membrane becomes the wall of the blood-vessels or arterial 

 capillaries. It is not only the spiroid thickening of the 

 inner coat, or spiral filament, that disappears, it is the inner 

 coat itself that stops and suddenly closes the aeriferous canal. 

 In this way we see, starting from a more or less voluminoiis 

 tracheal stem, very delicate blood-vessels, in larger or smaller 

 number, which divide and subdivide regularly to their 

 extremities. 



The blood retained in the peritracheal space remains 

 throughout its course in contact with oxygen ; it reaches the 

 capillaries perfectly vivified, and is a true arterial blood. 

 The capillaries are not in communication with venous capil- 

 laries ; the blood diffuses itself through the tissues, nourishes 

 them, and falls into the lacunae ; the lacunar currents convey 

 it aarain to the dorsal vessel. 



Thus, to sum up, the tracheae of insects, which are aeri- 

 ferous tubes in their central portion and blood-vessels in their 

 peripheral part, become at their extremities true arterial 

 capillaries. 



August. — " Note on the Microzymata contained in Animal 

 Cells,'''' by M. A. Estor. — The author makes additional re- 

 marks as to the evolution of Microzymata, or molecular granu- 

 lations, normally in cells of animals. These Microzymata, in 

 the conditions specified, group themselves two and two, or in 

 still larger numbers ; then elongate slowly, at length in such 

 a manner as to represent true Bacteria. These facts are the 

 results obtained from a great number of exj^eriments made 

 on different animals. The following observation shoAvs that 

 the same transformations may take place in man. A cystic 

 growth, cut out three days before, and filled with a half- 

 liquid, greenish matter, was submitted to a microscopic 

 examination. Microzymata at all periods of development 

 were observed : isolated granulations, others associated, others 

 a little elongated, and lastly true Bacteria. 



Robin's Journal de I'Anat. et de la Physiol — " Micrographic 

 Society of Paris." — The reports given in ' Robin's Journal' 

 of the meetings of this Society are very interesting, and show 

 that a great deal of real work is being done by its members. 



M. Balbiani drew attention, at the Fel)iuary meeting, to 

 the tubular prolongations of the nucleolus in certain cells, 



