68 BOTANICAL GAZETTE [TANUARY 
Plantago L. into two distinct species, as it was impossible, even by long continued 
cultures, to transform one into the other. 
Upon five of the forms special experiments to determine the influence of light 
were conducted. In general, however, the variable factor was the water relation, 
and this of course exercised some influence on numerous other relations. To 
change the degree or depth of submergence of a plant may not only alter the 
water relation, but cause as well differences in pressure, light, temperature, air, 
etc. It seems unfortunate that in all this study there was no exact attack upon 
certain of these factors individually, instead of the consideration of ensemble 
effects. Anatomical studies, too, would have been of interest, but the author 
felt he could not undertake the task at this time. 
Part IL is a summary of results. The plants are classed, without regard to 
systematic relations, into four habitat groups, viz.: land forms, shallow water 
forms, floating forms, and submerged forms. Each of these habitat groups is 
characterized by a certain type of leaf, though they of course intergrade. Each 
of these four dominant leaf types is discussed in relation to the environment 
producing it, especially the water relation. The optimum condition for general 
development was usually found to be shallow water. One plant, however, 
Echinodorus ranunculoides repens, grew best on land. 
In discussing the flowering habits of aquatic plants the author notes that the 
land and shallow water forms flower more freely, and he suggests a relationship 
— the leaf types and the flowering habits. It would seem, however, that 
planation might be readily thrown back, at least to the factors that produced 
the various leaf types. 
Three of the Alismaceae studied were able to develop flowers and to open 
them while wholly submerged. On bright days these flowers were observed to 
open in the water, each surrounded by a bubble of gas. Only one of these, A. 
graminifolium, was able to develop and ripen seeds without coming to the surface. 
- Metamorphosis of flowering shoots into leafy axes was accomplished by chang- 
ing the habitat. In Elisma natans and Echinodorus repens the amount of meta- 
morphosis was immediately correlated with degree of submergence. Beyond a 
certain depth only vegetative structures were developed. 
nder the head of formative factors the chief external influences discussed 
are those of water as such, depth of water, air, temperature, and light. The con- 
sideration of internal factors is limited to one—the quantity of reserve food. 
The author concludes with a summary, in Latin, of his systematic concep- 
tions of the forms studied.—Rosert B. WyLIE. 
The second volume* is concerned with the Utricularias of central Europe, 
the formation of turions by water plants, and Ceratophyllum. Gtick finds, 
4 GLtcx, Huco, Biologische und morphologische Untersuchungen iiber Wasse 
und Sumpgewiachse. Zweiter Teil: Un ntersuchungen iiber die mitteleuropaischen 
Utricularia-Arten; iiber die Turionenbildung bei Wasserpflanzen, sowie ti iiber Cerato- 
phyllum. 8vo. pp. xviiit+256. pls. 6 + figs. 28. Jena: Gustav Fischer. 1906. M. 18. 
* 
