ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 609 



to obtain the enzyme in as pure a state as possible, as impure pre- 

 parations were found to be strongly auto-digestive in acid or alkaline 

 media. The author found that the effects of poisons vary with the 

 purity of the preparation used, slight amounts of proteid impurities 

 Tendering necessary an enormous increase of concentration in order to 

 inhibit action. The toxic strengths of the salts used maintain a con- 

 stant relationship irrespective of the purity of the enzyme used, that is, 

 silver is always most poisonous, copper third, zinc sixth, and so on. 

 Pure preparations of bromelin, which, moreover, are not auto-digestive, 

 appear to be a mixture of two enzymes, one active in alkaline solutions, 

 slightly more resistant to poisons, and twice as great in amount as the 

 other, which is active in acid media, and is destroyed by heating to 

 65° C. in saline solution. The limits of toxicity and non-toxicity are 

 somewhat more clearly defined than has been the case in experiments 

 upon living organisms. The results obtained agree in general with 

 Mathew's arrangement of the metals upon the theory that " the affinity 

 of the atom or ion for its electrical charge is the main factor deter- 

 mining its physiological action." 



General. 



Botanical Relationship between Tropical Africa and America * — 

 A. Engler discusses somewhat fully the resemblances between the tropical 

 African and American floras. The most important cases of identity or 

 community of relationship between the seed-plants found on each side 

 •of the Atlantic are tabulated in twelve categories. In the majority of 

 these it is possible to assume the transport of fruit or seed across 

 the intervening ocean, but in several categories, which include forest, 

 water, marsh, and steppe plants, such means of transport cannot have 

 occurred. The author concludes that this community between the two 

 floras is best explained by assuming the existence of a land connection 

 between the district at the mouth of the Amazon and Biafra Bay in 

 West Africa, either in the form of large islands or a continent. He also 

 assumes a union between Madagascar and Natal ; the continuation of 

 this land mass in a north-easterly direction to Further India has long 

 been considered probable. The suggested Brazilian-Ethiopian con- 

 tinent must have existed in the Jurassic period. 



Flora of the Malayan Peninsula.f — A further instalment of King 

 and Gamble's Malayan Flora contains the second half of the Rubiaceae. 

 It includes descriptions of 23 genera, comprising 123 species, 47 of which 

 are new. 



Blanco's Flora de Filipinas.J — Elmer D. Merrill enumerates the 

 species described by Blanco, and in many cases is able to identify these 

 with species previously or subsequently described. Unfortunately none 

 of Blanco's specimens are extant, and his descriptions are often 



* SB. Preuss. Akad.. vi. (1905) pp. 180-231. 



t Journ. Asiat. Soc. Bengal, lxxiii. part 2 (1904) pp. 47-135. 



j Dept. Interior Bureau Gov. Lab. Manila, No. 27 (1905) pp. 1-132. I 



