March 21, 1902.] 



SCIENCE. 



463 



unfertilized egg. Two clear cases of 

 parthenogenesis among seed plants have 

 been published, namely, that of Anten- 

 naria, by Juel, in 1898, and that of certain 

 species of Alchemilla, by Murbeek, in 1901. 

 Dr. J. B. Overton, in a thesis about to be 

 I>ublished in the Botanical Gazette, an- 

 nounces the same phenomenon in Thalic- 

 truni ptirpurascens. In this last case the 

 segmentation of fertilized and unfertilized 

 eggs was compared. In the former case 

 the segmentation occurs synchronously 

 with that of the definitive nucleus, while 

 the unfertilized egg delays division until 

 the very numerous free endosperm nuclei 

 are parietally placed. It is surrounded by 

 a very dense mass of granular cytoplasm, 

 and associated with its segmentation are 

 striking changes in the zone of cytoplasni 

 immediately in contact with the egg. Over- 

 ton suggests the possibility of an enzyme 

 being secreted by the egg, and a digestion 

 of the cytoplasm. If this be the case, sub- 

 stances may well be developed in the 

 changing cytoplasm that will bring about 

 those physical changes in the egg that 

 induce segmentation. Observations in 

 other species were mentioned that indicate 

 the possibility that parthenogenesis may 

 be a much more common phenomenon 

 among seed plants than has been supposed. 

 The suggestion was also made that in any 

 embryo sac rich in cytoplasm a parthe- 

 nogenetic embryo may arise. 



The chairman called attention to the 

 model herbai'ium and the collection of 

 economic plant products at the Field Co- 

 lumbian Museum, to which the visiting 

 botanists would be admitted free on pres- 

 entation of their registration cards. In 

 conclusion he spoke of the interest in the 

 meetings, as evidenced by the large num- 

 ber who attended all of the sessions, and 

 of the fact that this third successful meet- 

 ing of the Botanists of the Central States, 



a body without organization, showed that 

 its success depended upon the spontaneous 

 interest taken in botanical work. 



Albert Schneidee, 



Secretary. 



SCIENTIFIC BOOKS. 



Towers and Tanks for Water Works. By J. 



N. Hazelhurst, Mem. Am. Soc. C. E. New 



York, John Wiley & Sons. 8vo. Pp. 216; 



19 illustrations. 



In this work the author has evidently aimed 

 not only to discuss those features of structural 

 design peculiar to stand-pipe and tank con- 

 struction, but also to include sufficient infor- 

 mation relating to some of the more general 

 matters as to make the volume com.plete in 

 itself. Out of the eleven chapters of the book 

 he thus devotes two chapters to the considera- 

 tion of the properties of iron and steel, two to 

 elementary mechanics, one to the subject of 

 foundations, and one to the painting of steel 

 structures. The remaining five chapters deal 

 more specifically with the design and con- 

 struction of tanks, although they also contain 

 much of a general and elementary character. 



While the engineer will find such subjects as 

 foundations, and iron and steel, much more 

 fully treated in special works, it is certainly 

 convenient to have in concise form such 

 information on these subjects as will be of 

 direct application to this particular field of 

 design. The chapter on painting is valuable 

 and quite in place here, owing to the great lack 

 of information on this important subject. The 

 subject of riveting is quite fully treated, and 

 convenient tables are given for the use of the 

 designer. 



In the chapters treating of the principles of 

 mechanics and their applications to the design 

 of the structures under consideration there is 

 much to be criticised. This portion of the 

 book is in fact full of the grossest errors of 

 theory, and were it not for the very absurdity 

 of the mistakes it would be unfortunate for 

 such a book to come into the hands of a young 

 engineer. The treatment of tanks is also very 

 incomplete, no consideration being given to 

 six- or eiglit-post towers and practically none 



