June 21, 1877] 



NA TURE 



147 



tributions to science recently made by Brandt, Middern- 

 dorf, Kowalewski, Radde, von Schrenck, and other dis- 

 tinguished names of the Academy of St. Petersburg, it 

 becomes somewhat ridiculous to a naturahst to hear the 

 oft-repeated assertion of the British patriot "that the 

 Russians are as great barbarians as the Turks ! " 

 Oscar Kertwig on the pHENOME>fA of Fer- 

 ' TILISATION.— The last number (Vol. iii., Part i) of the 



!*■ Morphologisches Jahrbuch, contains the second part of 



Oscar Hertwig's very important researches on the pheno- 

 mena immediately preceding the cleavage of ova in the 

 Echinoid Toxopneustes, in two genera of leeches, and 

 in the amphibia. He has watched most carefully the 

 process of fertilisation and the ova before fertilisation, 

 and has examined them after the action of various 

 reagents. His accounts are accompanied by very valu- 

 able figures. From his own observations, and a com- 

 parative study of other recorded facts, he appears to 

 have made generalisations worthy of the attention of all 

 biologists. The following is a brief summary of his con- 

 clusions. The unripe ovum is characterised by the 

 possession of a germinal vesicle, distinguished from all 

 cell-nuclei by its great relative size, by its definite mem- 

 brane, its more or less fluid contents, and its possession 

 of one or several nucleoli. The germinal vesicle in this 

 signification docs not become the nucleus of the first 

 cleavage-sphere ; in many animals it disappears long 

 before fertilisation, in other cases during that process or 

 during the ripening of the ovum. At any rate the germi- 

 nal vesicle loses all its distinctive characters. The active 

 nuclear substance, or a part of it, remains and forms a 

 new nucleus of much smaller size, lacking a distinct mem- 

 brane and true nucleoli. From a highly differentiated 

 form is produced a primitive nucleus ; instead of a ger- 

 minal vesicle we have an ovinucleus. In To,\opneustes the 

 retrogression of the germinal vesicle is accompanied by its 

 movement to the outer surface of the yolk, where it disap- 

 pears, with the exception of the germinal spot ; the latter 

 again reaches the centre of the yolk and becomes the 

 nucleus of the ripe ovuii^. In Hirudinea; there is an acces- 

 sory prelude to fertilisation, the budding-off of "directive 

 bodies " immediately after oviposition. After this arises a 

 spindle-shaped ovinucleus really derived from the breaking 

 up of the germinal spot. In amphibia the exceedingly large 

 germinal vesicle gets to the surface and disappears. 

 Only a small portion, one or more nucleoli, passes over 

 into the inconsiderable ovinucleus. The parts of the 

 germinal vesicle not contributed to the ovinucleus seem 

 no longer serviceable, and get transformed into the so- 

 called excretory bodies and sphere. In Amphibia a mass 

 of this kind appears as a yellowish covering over the dark 

 pole of the egg. Like Toxopneu5tes appear to be Me- 

 duss, Siphonophora, Ascidians, some Vermes, Arthropods, 

 &c., possessing in the ripe and unfertilised ova a small 

 homogeneous, membraneless nucleus in the middle of the 

 yolk or on its periphery. The Hirudines resemble Gas- 

 teropods, Heteropods, Pteropods, and some Vermes. Here 

 the ripe egg has mostly on its periphery a small spindle- 

 shaped nucleus. In fishes and reptiles, as in the frog, there 

 is a germinal vesicle with many nucleoli, some of which 

 form the ovinucleus. After this stage Hirudineae twice 

 exhibit a budding from the surface of the ovum forming 

 the so-called directive bodies, the ovinucleus contributing 

 to them. The actual occurrences of fertilisation cor- 

 respond very closely not only in animals but in plants. 

 In Toxopneustes a single spermatozoon reaches the ripe 

 ovum and is transformed into a small corpuscle, the 

 sperm-nucleus, surrounded by a protoplasmic rayed figure. 

 It travels in from ten to fifteen minutes to the central ovi- 

 nucleus and is fused with it. In Rana teinporatia the 

 spermatozoon enters at the side of the excretory body and 

 becomes like that of Toxopneustes, travelling to the ovi- 

 nucleus and fusing with it. In Hirudineae the sperma- 

 tozoon enters subsequently to the budding of the first 



directive body, and after transformation gets to the centre 

 of the ovum and there remains till the budding of the 

 second body. Then the ovinucleus travels to the centre 

 and is apposed to and fuses with the sperm-nucleus, 

 which has swollen considerably. Thus in these cases 

 the cleavage-nucleus is formed by the union of the two 

 sexually-ditferentiated nuclei. 



Individual Variations in Animals.— At the last 

 meeting of the St. Petersburg Society of Naturalists, Prof. 

 Wagner made a communication "On the Individual Varia- 

 tions in Animals, their Causes, and Results." Pointing out 

 that the appearance of new races, varieties, and species is 

 rendered possible bytheappearance,at all stages, of the de- 

 velopment of life of individual variations, which variations 

 give rise afterwards to more or less constant new forms, 

 the Professor sketched the causes of these individual varia- 

 tions, exterior and interior, insisting especially on the 

 importance of these latter. The causes of variability, he 

 said, are not only the physico-chemical influences of the 

 medium inhabited by the individuals, i.e., the exterior 

 causes, but also, to a very important degree, the interior 

 causes, i.e. those subjective physiological, and therefore 

 also psychological, individualities which characterise each 

 individual, and whicii mo.lify to a considerable extent the 

 influence of exterior influences on each separate represen- 

 tative of the species. 



A New Cheetah. — At the meeting of the Zoological 

 Society on Tuesday last, Mr. Sclater described a new 

 species of cheetah, from South Africa, differing from Felis 

 jiibata in the fact that the whole body is covered with 

 spots of a dark yellow instead of black, and at the same 

 tune is considerably more thickly covered with hair. Mr. 

 Sclater proposed the name Felis lanea for this apparently 

 new species. 



North American Lepidoptera. — Mr. William H. 

 Edwards has published a catalogue of the diurnal lepi- 

 doptera of North America and Northern Mexico, supple- 

 menting the well-known work by Dr. Morris, printed 

 some years ago by the Smithsonian Institution. He 

 enumerates no less than 506 species. This is abojt 

 equal to that of the previous catalogues, the addi- 

 tional new species being balanced by canceling names 

 which were synonyms or not legitimately entitled to 

 introduction in the North American list. The special 

 object of Mr. Edwards is to bring about what he considers 

 a satisfactoiy nomenclature, dissenting from the radical 

 changes which he insists Mr. Scudder has made in his 

 recent divisions and lists, in few of which he concurs. 



A New Shell.— Mr. C. R. Thatcher, the experienced 

 conchological collector, has just returned to this country 

 after a five years' collecting journey through China, 

 Japan, Philippine Islands, and Australia. He has pro- 

 cured several new species of Murex, Cancellaria, and one 

 wonderful specimen of an entirely new genus. This 

 specimen was described at the meeting of the Zoo- 

 logical Society on Tuesday, June 5, by Mr. George French 

 Angas, by whom it is proposed to give the name 

 Thatcheria, in honour of its discoverer. It was the travel- 

 ler's particular aim to procure specimens of the rare 

 Cyprcca thatcheri and Valuta thaUhcri, both of which he 

 found a few years ago, for whicn purpose he travelled 

 many hundreds of miles into the interior of Japan, often 

 at the risk of his life. 



GEOLOGICAL NOTES 

 Rare Minerals in the North of Scotland. — 

 The accidental use of a mass of granite for building pur- 

 poses near Tongue, in Sutherlandshire, has led to the 

 detection of several rare minerals, and of quite a remark- 

 able number of species and varieties associated in the 

 same mass of rock. From among the frai;ments of the 

 boulder pieces of a bright green stone were sent to the 



