234 



SCIENCE 



[N. S. Vol. XXXI. No. 789 



member of the Molgophidse as one of these 

 connecting types. This localized specializa- 

 tion means that we must look into the Missis- 

 sippian and the Devonian for the earliest of 

 the Amphibia in North America, as the foot 

 prints which have been discovered in these 

 deposits would indicate. 



The discovery of the new temnospondylous 

 form with other facts of the distribution of 

 the Temnospondylia indicates that the order 

 originated in North America. At least the 

 earliest known forms occur in this continent. 



The amphibian fauna of Mazon Creek at 

 the present time may be regarded as repre- 

 sented by nine species which are members of 

 four orders and five families. The orders 

 are: Branchiosauria, Microsauria and Temno- 

 spondylia. An additional fact of interest is 

 the discovery of osseous branchial arches in an 

 imperfectly preserved specimen; the second 

 species from the Pennsylvanian in which these 

 structures have been seen. This means the 

 presence of a fourth order of Amphibia in the 

 Mazon Creek shales. 



EoT L. MOODIE 



The University of Kaksas, 

 January 14, 1910 



^ A FIXING FLUID FOR PLANT TISSUES 



My experience with Bouin's fluid as a fixing 

 material for certain plant tissues for cyto- 

 logical work has been so satisfactory that I 

 take this opportunity of recommending it to 

 plant cytologists as one which combines a 

 number of admirable features. It has, of 

 course, been used for a number of years in 

 connection with animal tissues, and especially 

 for studies of spermatogenesis, in which it 

 gives notably clear preparations. I first tried 

 it, along with a number of other solutions, for 

 fixing anthers of CEnothera, in 1908. The 

 formula used was as follows: 



Parts 

 Picric acid, saturated aqueous solution . . 75 



Glacial acetic acid 5 



Formaline 20 



Of course, various modifications of this may 

 be found advantageous for different plant 

 forms. 



The time of fixation must be short, other- 

 wise maceration results. It should probably 

 not exceed four to six hours. The time of 

 washing must also be comparatively brief, as 

 long washing causes deterioration and frag- 

 mentation of the material. CEnothera an- 

 thers, after a few hours' immersion in this 

 fiuid, frequently acquire a slight pinkish tint, 

 which remains indefinitely after the material 

 has been dehydrated and placed in VO per cent, 

 alcohol. 



This solution seems to be a favorite one for 

 studies on animal spermatogenesis, and I see 

 no reason why it should not become popular 

 also for various purposes in plant cytology. 

 Its obvious advantages are (1) that, unlike 

 osmic solutions, it leaves the tissues clear and 

 transparent, (2) its penetration seems to be 

 very rapid, giving an even and almost perfect 

 fixation of the material, (3) it leaves the cyto- 

 plasm and nuclei perfectly colorless, giving 

 particularly clear and brilliant results in 

 staining chromatin and spindles when fol- 

 lowed by Heidenhain's iron-hsematoxylin 

 stain. 



K. E. Gates 



Missouri Botanical Gakden 



TUB AMERICAN SOCIETY OF NATURALISTS 

 The American Society of Naturalists met at 

 the Harvard Medical School, Boston, Mass., on 

 Wednesday, December 29, 1909. There were both 

 morning and afternoon sessions. The program 

 consisted of original papers and demonstrations 

 of studies on evolution, and the meeting proved 

 to be one of the most successful in the history of 

 the society. The variety and importance of the 

 papers read are well shown by the following list 

 of titles: 



PAPERS 



U. Dahlgren : " Origin of the Electric Tissues 

 in Teleost Fishes" (lantern). 



D. T. MacDougal : " Origination of Parasitism 

 in Higher Plants." 



F. Boas : " The Influence of Heredity and of 

 the Environment on Man." 



E. Brainard: "The Evolution of New Forms in 

 yiola through Hybridism." 



R. R. Gates : " The Material Basis of Mendelian 

 Phenomena " ( lantern ) . 



A. M. Lutz: "The Relation of Chromosome 



