222 BOTANICAL GAZETTE [MARCH 
branches to erect themselves or in other cases to develop, though they have the 
same tendency to do so as he; their geotropism or their power of growth is held 
in check by his own. Suppress the apex, let it die or become enfeebled, and the 
subjugated branches lift their heads. Several could erect themselves and take 
the lead, and that is sometimes observed. But ordinarily a new conflict for 
precedence occurs among the branches; the one nearest the apex or the most 
vigorous near one early asserts its supremacy and in its turn keepsits rivals at its 
feet. Cj. the independent and almost simultaneous amas of the like idea 
y McCattium, Bot. GAzETTE 40 : 262. Oct. 1905.—-C. R 
Ecological survey.—P 1 PRAEGER?° have a8 another vegeta- 
tion map and ecological description to the list of vegetation surveys of the British 
Isles. The area discussed lies south and west of Dublin. After a historical 
introduction the geology, physiography, floristics, and survey methods are briefly 
explained. The vegetation is divided primarily into littoral, agrarian, hill- 
pasture, and moorland zones, and the woodlands. The zones are further sub- 
divided into associations. These are described in detail and as far as possible 
related to the factors determining their occurrence. The text is accompanied 
by a map and five excellent plates of vegetation types. The paper will prove of 
especial interest to those who have followed the work of R. SmitH, W. SMITH, 
and Lewis in Scotland and England.—E. N. TRANSEAU. 
Alternation of generations in animals.—In criticism of CHAMBERLAIN’S paper 
on this subject?? Lyon?? holds that the phylogeny of animal gametes gives no evi- 
dence of their being reduced or vestigial generations, comparable with the gameto- 
phytic generation in plants; similarity of cytological processes does not prove 
identity of morphological value in the two cases. He refers to the alternation in 
Hydrozoa, and calls attention to the earlier proposal by BEARD and MuRRAY of 
a theory similar to CHAMBERLAIN’s. In reply CHAMBERLAIN maintains’$ that his 
-critic fails to distinguish between a gametophytic generation and a gametophytic 
plant. He holds that the generations in Hydrozoa do not alternate in the 
botanical sense, and points out that although reduction of the gamete-bearing 
generation has not been proved for animals, there is strong evidence for its 
aving occurred in plants—M. A. CHRYSLER. 
Mechanics of secretion.— PANTANELLI*4 has attempted to ascertain whether 
or not true secretion of enzymes occurs. He defines secretion as “‘the emission 
2°PETHYBRIDGE, G. H. and PRAEGER, R. L., The vegetation of the district lying 
south of Dublin. Proc. Roy. Irish Acad. B. 25:124-180. 1905. 
2tBoT. GAZETTE 39: 137-144. 1905. 
22Lyon, H. L., Alternation of generations in animals. Science N. S. 21: 666-667. 
05. 
?3CHAMBERLAIN, C. J. Alternation of generations in animals. Science N. S. 22! 
208-211. 1905. 
?4PANTANELLI, E., Meccanismo di secrezione degli enzimi. Annali di Bot. 3: 
i13-142. 190 
