20 Beiblatt zu den Botanischen Jahrbüchern. Nr, 70. 
Centrum vegetationis — Vegetation centre. 
Lineamentum — Line of stress. 
VIII. Terms for Physical Factors and Instruments !). 
Temperatura — Temperature: thermotropismus, thermotaxis, ete.?). 
Maximum, minimum, optimum, pessimum, isophytotonus: thermometrum, 
thermometer. 
Lux — Light: phototropismus, phototaxis, etc. 
Intensitas, duratio, qualitas, directio: photometrum, photometer. 
Aqua soli — Water content: hydrotropismus, hydrotaxis, etc. 
Physica, physiologica: geotome geotome. 
Solum — Soil: chemotropismus, chemotaxis, ete. 
D , 
Textura, pressura, porositas, capillaritas: rhoptometrum (pozzów, tó, what 
is absorbed), rhoptometer; atmometrum (Atuss, ó, vapor), atmo- 
meter. 
Atmosphaera — Atmosphere. 
Humiditas (psychrometrum), aura (anemometrum, index ventorum), pres- 
sura (barometrum), compositio, praecipitatio (ombrometrum). 
Physiographia — Physiography. 
Altitudo (barometrum), exposura, clivus (clinometrum), superficies: acus 
magnetica, compass. 
Gravitas — gravity: geotropismus, geotaxis, ete. 
Franautr has rightly insisted that his propositions with regard to no- 
menclature are to be regarded as suggestions only, and that for such a 
work the collaboration of botanists of all nationalities is necessary. This 
must be true of all proposed systems at present. We are merely on the 
threshold of the development of phytogeography. Some of its aspects, 
such as the phylogeny of vegetation, and experimental field ecology, have 
scarcely been touched, while its very foundation, the exact investigation of 
ils physical basis, the habitat, is yet to be laid. Until the latter is done, 
the limitation of many formalions will be uncertain, if not impossible, and 
the application of formational terms more or less inexact. Phytogeographers 
should hold themselves fortunate, however, that the nomenclature discussion 
has arisen so early, before hard and fast lines have been drawn, and be- 
fore names and terms have become fixed in the minds of botanists. War- 
BURG has well said that the time is especially favorable for this work — 
more favorable indeed than it ever can be again. The feeling for a thorough 
and scholarly system of nomenclature is growing. It is all important to 
take advantage of this fact before phytogeography becomes encumbered 
with a nomenclature that has »jest growed«. 
1) Pounn and Cements Le 464. 
2) Davenport, C. B., Experimental Morphology, 1897. 
