NOTES AND MEMORANDA. 55 



and single cell. According to oui* monistic conception of tlie cell- 

 soul, we must suppose that the fertilized ovum already possesses 

 virtually those psychic properties which in the particular mixture of 

 parental peculiarities (i. e. those of mother and father) characterize 

 the individual soul of the new being. In the course of the develop- 

 ment of the ovum the cell-soul of course develops itself simul- 

 taneously with its material substratum, and becomes apparent actually 

 when the child is born. According to Virchow's dualistic conception 

 of the ' Psyche,' we must suppose, on the contrary, that this im- 

 material being enters the soulless germ at some period of embryonal 

 development (perhaps when the spinal tube separates from the germinal 

 lobe?). Of course in this way the pure miracle is complete, and the 

 natural and uninterrupted continuity of deielopment is superfluous." * 



Post-embryonic Formation of Appendages in Insects. — H. Dewitz 

 was led by Darwin's remarks in the ' Origin of Species,' on the 

 difficulty offered to the doctrine of natural selection by the neuters of 

 ^insects living in communities, to make some researches on this 

 subject, the results of which he sums up as follows: | — 



The workers of ants possess very small wing-disks, situated 

 precisely as in winged insects, and undergoing subsequent retro- 

 gressive metamorphosis. A figure is given, showing a rudiment of 

 the posterior wing in an adult worker. 



The thoracic appendages of ants first appear as a disk-shaped 

 thickening of the hypodcrmis, which becomes separated into a 

 central portion, the rudiment of the leg or wing, and a surrounding' 

 membrane ; an aperture, opening outwards, being left in the latter. 

 The membrane grows as a sack- or pocket-shaped invagination, into 

 the interior of the body, and when metamorphosis takes place, the 

 original aperture is enlarged to allow of the extrusion of the limb. 



The young thoracic appendages of ants and bees secrete a 

 chitinous cuticle during the larval condition. The difference betsveen 

 the limbs, formed during post-embryonic life, of Holomctabola and 

 of Ametabola, does not consist in the formation or non-formation of 

 this cuticle, but in the fact that in Holometahola the newly formed 

 appendages lie for the most part concealed in invaginations of the 

 hypoderm, making their appearance first iu the pupa sta«e, while 

 in Ametahola they are visible from the first. 



The formation of the wings of LepidojJtera, and, in the author's 

 opinion, that of the appendages of all insects, takes place from the 

 hypoderm, although probably their internal differentiation is always 

 brought about by the penetration into them of nerves, trache®, &c. 



The main difference between the females and workers of ants is 

 not produced as in bees, by a different treatment of the eggs or ]arv» 

 on the part of the adult workers, but the future fate of the e^^g is 

 settled while still in the body of the mother. 



The "Weber Slide. — The well-known live-box or animalcule cawe 

 serves the purpose of preserving and exhibiting living objects very 



* 'Nature,' vol. xix. p. 113. 



t 'Zeitsch. f. wiss. Zool.,' vol. xxx. (Suppl.), p. 78. 



