NATURE 



49 



THURSDAY, MAY i6, 1907. 



DF.VELOPMENT OF THE HUMAN EMBRYO. 



HiJiidatlas dcr Eniwickhingsgeschichte des Menschou 

 By Prof. Julius Kollmann. Part i. Pp. viii + 340 

 figures, many of them printed in several colours, 

 with a brief explanatory text. (Jena : Gustav 

 Fischer, 1907.) Price 13 marks. 



THO.se who wi.sh to see at a glance a truthful 

 and graphic representation of our present know- 

 ledge concerning the conception and development of 

 the human body will find it in this hand-atlas by 

 Prof. Kollmann. Here is a museum rather than a 

 book, a museum in which specimens illustrating 

 nearly all stages of development have been judiciously 

 collected from the best sources — many of them from 

 the shelves of the author's own museum — and repre- 

 sented by all the skill of modern pictorial art, a brief 

 description being given of each specimen to supply 

 the place of a catalogue. Altogether, this work will 

 contain 800 figures illustrating stages in the develop- 

 ment of the human body. 



Five-and-twcnty years ago our knowledge of the 

 human embrvo, if not a complete blank, was almost 

 a complete series of blanks. When the late Prof. 

 His published his great monograph on the early 

 human embryo in 1882, he was able to find accounts 

 of only ten specimens belonging to the first month 

 of development, these accounts being, for the greater 

 part, imperfect descriptions of the external appear- 

 ances of poorly preserved embrvos. The rapid pro- 

 gress which has made the production of this hand- 

 atlas possible was the result of the application of a 

 new method by which the minute and exceedinglv 

 delicate embryo could be cut, fixed, sectionised, and 

 accurately reconstructed on a magnified scale. The 

 reconstructional method gave embrvologists an easy 

 means of mutual exchange ; by a reconstructed 

 model it became possible to show accuratelv in five 

 minutes w-hat had been acquired by five months of 

 labour. The method of reconstruction by wax plates 

 is usually ascribed to Prof. Born, but the late Prof. 

 G. B. Howes claimed the invention for Mr. E. T. 

 Newton, who applied it to the reconstruction of the 

 brain of insects before 1S78. This laborious method 

 has never appealed to the English anatomist; hence 

 we find that not one of the forty-four specimens which 

 Prof. Kollmann uses to illustrate the stages of de- 

 velopment in the first and second months was pre- 

 pared in England; the reconstructed models of which 

 illustrations are given were made in the laboratories 

 of Germany, Switzerland, and America. Yet the 

 method by which progress has been attained was 

 first used in England ; nor were human embryologists 

 lacking in England in the early days, for when Prof. 

 His began his great work he counted that of the 

 late Prof. .Allen Thomson amongst the best. How far 

 we have lost preeminence in this subject may be seen 

 from the fact that in the 340 illustrations used in the 

 first part of this atlas, only one is the work of a British 

 anatomist, and that is a diagram published a good 

 many years ago by Sir \\'illiam Turner, of Edinburgh. 

 NO. 1959, VOL. 76] 



It has always been the habit to utilise our know- 

 ledge of the developmental history of the domestic 

 animals to fill in the blanks in the history of human 

 development. That is now unnecessary except for 

 (he first week; Leopold's ovum represents the earliest 

 stage of human development, and it is probably in 

 the seventh or eighth day of growth. The fertilisa- 

 tion and segmentation of the human ovum have not 

 vet been seen, but it is highly improbable that they 

 will present anv peculiar features. To supply this 

 blank. Prof. Kollmann reproduces the excellent illus- 

 trations of the fertilisation of the mouse's ovum given 

 bv Sobotta, and those of the segmentation of the 

 ovum of the dog and bat depicted by Bonnet and 

 van Beneden. The author also realises the great 

 value of comparative embryology as a key to the more 

 obscure processes of human development, and draws 

 frcelv on the work of van Wijhe, Flemming, van der 

 Stricht, Hertwig, Froriep, Stiihr, and Schauinsland. 

 .Abnormalities of development are also illustrated. 



There was a general expectation that a complete 

 knowledge of the phases of embryonic development 

 would give a key to the origin and past history of 

 man. That expectation has not been fulfilled. If to 

 some extent developmental phases do recapitulate 

 certain generalised stages of evolution, yet so blurred 

 are thev, so much are they modified by the conditions 

 of foetal growth, that they give us no certain know- 

 ledge. In the excellent series of models which the 

 author uses to illustrate the transformations at the 

 end of the first month and beginning of the second 

 one can see the gill arches and cleft appear and then 

 disappear, the tail bud out and then become sup- 

 pressed. But even in these early stages it is to be 

 seen that the brain is planned on a large scale ; Prof. 

 Kollmann reproduces side by side a human embryo 

 in the second month of development with that of an 

 ape (Macaciis cynomolgus) in a corresponding phase; 

 superficially they look wonderfully alike, especially as 

 regards their limbs, but the human head, if the same 

 in type, already shows a distinct difference in form 

 and proportion. It is too soon to say how far embry- 

 ology may yet throw light on the relationship of 

 man to other Primates. We know practically nothing 

 of the embryology of the anthropoids which are most 

 closely related to man. Thanks to the labours of 

 Selenka, which are freely used by Prof. Kollmann, 

 we know a good deal of the early history of one 

 anthropoid, the gibbon, and in it the process by which 

 the ovum becomes embedded in the uterus is identical 

 to that in man and differs from that of the common 

 ape. That was to he expected from what is known 

 of their anatomy. It is possible, too, that the investi- 

 gations which are being made in America by Mall, 

 Bardeen, and Lewis on the later stages of the develop- 

 ment of the human embryo — the formation of the 

 bones and muscles of the limb and trunk — may give 

 definite bearings as to man's relationship to other 

 Primates. All the present evidence for the solution 

 of such problems has been brought together and made 

 available for those who are interested in this sub- 

 ject by Prof. Kollmann. The price of the hand-atlas 

 is so low- that one marvels how the venture can be 

 m.ide to pay. 



D 



