NOTES AND MEMOBANDA. 399 



fresh pulsating heart did not present any blood-cells with processes 

 of any great length, but in about a minute observation revealed their 

 presence ; the same results were obtained with blood taken from the 

 vessels, and the conclusion is arrived at that in the circulating blood 

 the cells only give off a few and those short processes ; it is obvious 

 that the presence of large conglomerate masses would effectually stop 

 up the smaller blood-vessels, and it is observed that it is rare for such 

 masses to be observed in fresh blood. 



At times a few immobile bodies without processes, and of a smaller 

 size, were also observed ; these might be rounded or formless, and 

 present or not present distinct nuclei. 



Later Stages in the Development of Fresh-water Mussels.— 

 M. Blanchard gives * an account of Max Braun's observations."]" 

 These were rendered successful by cutting up the gills of a female 

 Anodon, and so separating the embryos therein contained, and 

 placing them in an aquarium in which were a number of fish ; on 

 these Vertebrates the embryos soon fixed themselves and attained 

 their adult stage in something over seventy days. Having fixed 

 themselves by their byssus-threads, the so-called Glochidia fasten their 

 shells into the fins or other parts of their hosts ; the inflammation so 

 started gives rise to a proliferation of epithelial cells, in which the 

 larvae are soon encysted. As may be imagined, observations on their 

 development were thus rendered easy, and Braun is able to state that 

 the byssus-gland soon disappears, that the single adductor muscle 

 of the valves, having become double, soon makes way for dther organs, 

 while the permanent adductors become developed ; the foot appears 

 at first as a cone situated in the middle of the larva, and the pedal 

 ganglia become evident ; the median portion of the enteric tube gives 

 rise to two hepatic caeca ; the mantle of the embryo, which consists of 

 large cylindrical cells, disappears, and the new mantle, which is 

 made up of small cubical cells, takes its place. This absorption is 

 accompanied by that of the bony ray of the fin to which the embryo 

 had become attached, and the calcareous salts from it appear to go 

 to form the shell of the adult. The generative organs are not 

 developed till later, and when the young is set free from the cyst. 



Locomotion of the Terrestrial Gasteropoda. — Heinrich Simroth 

 has an interesting article on this subject, | which is one on which little 

 has been done of late, and the views of Bergmann and Leuckart are 

 still accepted by most zoologists. According to these observers the 

 mechanism of locomotion in the common garden snail is essentially 

 the same as in a number of apodal insect-larvEe, with this exception, 

 that the number of waves which pass over the body are much more 

 numerous, and the attachment of the foot to the surface moved over 

 is more complete. There is, of course, no doubt that locomotion is 

 effected by the waves which pass over the foot from behind forwards, 



* « Kev. Internat. rles Sci.,' il. (1S7S) 634. 



t ' Verh. Phys.-Med. Gesellscli. Wurzburg,' xiii. ; SB., p. xxiv. (4th May, 1878). 



X ' Zeitsch. f. wiss. Zool.,' xxx. Suppl. (1878) 166. 



