NA TURE 



171 



THURSDAY, AUGUST 10, 1911. 



GYMNOSPERMS. 

 Morphology of Gymnosperms. By Prof. J. M. Coulter 

 and Prof. C. J. Chamberlain. Pp. xi + 458. 

 (Chicago : The University of Chicago Press ; 

 London : Cambridge University Press, 1910.) Price 

 16s. net. 



IN 1 00 1 Profs. Coulter and Chamberlain published 

 a short treatise on the Gymnosperms, forming 

 the first volume of their " Morphology of Spermato- 

 phyta." Their present work takes the place of this 

 volume, and is practically a new book, designed on 

 a far more liberal scale than its predecessor. The 

 number of pages has grown from 188 to 458, and 

 the illustrations have increased in an even greater 

 proportion. The extension of the book is in no small 

 degree due to the ordinal researches of the authors 

 and their pupils ; the special contributions from the 

 Chicago laboratory have amounted to twenty-six since 

 1901. 



"The present account, therefore, is based upon our 

 own work, supplemented by the work of other in- 

 vestigators, rather than a compilation from literature, 

 supplemented by occasional personal observations " 

 (preface). 



A striking feature of the book is the prominence 

 now given to palasobotanical evidence. 



The book is an invaluable record, admirably illus- 

 trated, of our present knowledge of the older type of 

 seed-plants; on reading- it one is enabled to realise 

 in what respects essential progress has. been made, 

 and where, in spite of the accumulation of detail, there 

 has been little real advance. The latter, less favour- 

 able position exists, in the reviewer's opinion, in 

 respect of the Conifers, in which the most funda- 

 mental points of morphology and affinity still remain 

 obscure. 



The book begins with an account of the Palaeozoic 

 class, Cycadofilicales, a name which the authors 

 prefer to the more modern designation, Pteri- 

 dospermeae, now generally adopted in England and 

 France. The authors are certainly well- advised to 

 include a description of the Pteridosperms in their 

 book, though some botanists have thought it best to 

 keep these fern-like seed-plants of the Palasozoic apart 

 from the Gymnosperms, on the ground of their mani- 

 festly primitive characters. In this book there is a 

 tendency to minimise the peculiar features of the 

 Pteridosperms, which mark them off as an archaic 

 group. The entire absence of anything approaching 

 to a strobilus separates them, among other characters, 

 from all Gymnosperms except the female plant of 

 Cycas. In any case, however, the close relations 

 between the seed-ferns and the true Gymnosperms 

 are undisputed and of fundamental importance. 



The Cycadofilices were recognised as a distinct 

 group before their reproductive organs were dis- 

 covered. The authors scarcely do justice to this 

 rather impressive instance of the successful use of 

 anatpmical characters in determining systematic posi- 

 tion ; they say : — 



NO. 2l8o, VOL. 87] 



"The striking anatomical feature of the Cycado- 

 filices is the association of secondary wood with a 

 fern-like vascular system. There was no occasion, on 

 thi^ account, to remove Cycadofilices from Pteri- 

 dophytes " (p. 2). 



No one who knew Williamson's work was likely 

 to found a new group on such a basis; other con- 

 siderations, as, for example, the close agreement 

 between the leaf-trace strands of Lyginodendreas and 

 those of Cycads carried much more weight; the 

 authors appear in this instance not to have consulted 

 adequately the original memoirs. They do full justice, 

 however, to the importance of the work done in recent 

 years on morphological anatomy, especially that of 

 the vascular system : — 



"Vascular anatomy has emerged as a subject 

 organised upon a morphological basis, and its value 

 in supplementing the older morphology cannot be 

 overestimated " (p. 4). 



Though open to some criticism in detail, the account 

 given of the Pteridosperms is on the whole an excel- 

 lent summary, and will be welcomed by readers who 

 are not familiar with special works on palaeobotany. 



The interesting question of the constant absence of 

 an embryo in all Palaeozoic seeds hitherto investigated 

 is discussed. This has been regarded as the normal 

 condition, the development of the embryo not having 

 begun until after the seeds were shed, and then 

 having passed over at once into germination. The 

 authors, on the other hand, incline to the view that 

 all Palasozoic seeds investigated were abortive, having 

 been shed prematurely. The fact that nearly all the 

 seeds observed are at the same stage of development, 

 and the usual presence of normal pollen in the pollen- 

 chamber scarcely seem consistent with this view. 



The remark that the seeds of Pteridosperms 

 "are very far from being primitive in structure, and 

 are no more suggestive of the origin of seeds in 

 general than are the seeds of existing seed-plants 

 (P- 34). 



appears just, and indicates how much remains to be 

 learnt in this field. 



In discussing the relations of the Pteridosperms 

 to the ferns it is pointed out that " Filicales are prob- 

 ably so ancient that all of our evidence is relatively 

 modern " (p- 5S). 



"The gap between the homosporous Primofilices 

 (or their unknown ancestors) and the seed-bearing 

 Cycadofilicales is an enormous one, including the 

 evolution of both heterosporv and the seed ' (p. 57). 



The authors divide Gymnosperms into Cycadophytes 

 and Coniferophytes (the latter name too glaringly 

 hybrid to be acceptable). They include the Cycado- 

 fiiicales in the former, which is not Nathorst's arrange- 

 ment, as erroneously stated on p. 59. The two great 

 phyla are regarded as "both differentiating from the 

 Cycadofilicales or each arising independently from the 

 progenitors of the Cycadofilicales " (p. 59)- Th!s is a 

 little confusing, for on the former alternative the 

 Cycadofilicales would have differentiated from them- 

 selves. It would have been better to leave the Cycado- 

 filicales (Pteridosperms) as an independent ancestral 

 group, lying at the root of all the other branches. 



