ZOOLOGY. 365 



therefore the fluidity of blood, depended. The peculiarity of this demon- 

 stration of the cause of the fluidity of the blood is, that it explains the differ- 

 ent hypotheses which have previously been offered on this question, and 

 shows in how far these hypotheses have approached or fell short of the 

 truth. In concluding his paper, Dr. Richardson pointed out that ammonia, in 

 combination with carbonic acid gas, is a constant constituent of the air 

 expired in the breath. The presence of ammonia hi the animal economy, and 

 its evolution in respiration, w r as of interest hi that it connected more closely 

 the limit that exists between the animal and vegetable worlds. But the sub- 

 ject was of the greatest importance in relation to the causes, the nature, and 

 the treatment of various diseases. 



OX THE PROPAGATION OF OYSTEPtS. 



Mr. T. C. Eyton, in a report to the British Association at its last meeting, 

 on the oyster beds and oysters of the British shores, stated, that he had found, 

 on examining the spawn of three oysters, on a rough calculation the number of 

 young was about three millions ; they were semi-transparent, with two red- 

 dish elongated dots placed on each side, behind the ciliee, which were in 

 constant motion, and they are exceedingly tenacious of life. From observ- 

 ations made, it appears that the month might be advantageously altered hi 

 many beds, so that the markets might be supplied throughout the greater part 

 of the year. The depth of water is the chief cause of the different time of 

 spawning. The common opinion that oysters spawn in masses is erroneous ; 

 and for the benefit of oyster-eaters, it appears that they are best for the table 

 out of shallow water and at the entrance of rivers, as they feed quicker in such 

 situations. 



OX THE DICECIOUS CHARACTER OF THE ROTIFERA. 



Mr. Gosse, in a communication to the Royal Society, shows that Ehrenberg's 

 conclusions respecting the hermaphrodite nature of the Rotifera are not borne 

 out by facts. In 1848, Mr. Bright well announced his important discovery of 

 separate sexes in a Rotiferous animal, since named Asplanclma. The dioecious 

 character has been subsequently extended from a species to a genus, and from 

 the various analogies which have been discovered between them and other 

 animals, Mr. Gosse assigns to the Rotifera a zoological position among the 

 articulata. 



CURIOUS AXATOMICAL COLLECTIOX. 



M. Serbes, of the Jardin des Plantes, Paris, availing himself of the oppor- 

 tunity which the war in the East afforded of collecting a great variety of 

 types of human heads, until now unrepresented in the museums of Europe, 

 directed the persons in charge of the French Hospitals at Constantinople to 

 make the desired collection and send it to him. These heads were preserved, 

 just as they were severed from the body, by means of a new process dis- 

 covered by M. Roux, of Paris. The process consists in placing around the 

 dead matter first, earth on which sulphuric acid has been poured, and with 



