34 HOPKINS: BIOCLIMATIC LAW 



with an agreeable odor when fresh; embryo 2 cm. long, 1.2 cm. broad, 

 flattened, yellowish white, with a dark umbilical area on the outer 

 thicker margin. 



Type in the U. S. National Herbarium, no. 601496, collected at La 

 Trinidad de Maracay, State of Aragua, Venezuela, at an altitude of 

 about 440 meters, in flower, January 31, 1913, by H. Pittier (no. 5789). 



The purpose of the spongy suberose tissue surrounding the embryo 

 is to store moisture for the promotion of germination. 



To my knowledge, Swietenia Candollei is spread in the basal region 

 all over the coastal range of Venezuela and in the interior valleys 

 north of the llanos. A tree which is presumably this species is reported 

 to e^ist in the Orinoco Valley also, and along the foot of the Andes in 

 the region of Lake Maracaibo, but until we have specimens it is not 

 possible to affirm that there is but a single species in these regions. 

 Several other timber trees belonging to diverse genera are in the local 

 market under the name caoha, which is the Spanish equivalent for 

 mahogany. 



The Venezuelan mahogany is often seen along streets and in parks, 

 as for instance in Valencia, in the State of Carabobo. It is used also 

 for shade or as a windbreak in cacao plantations and in former times 

 was planted extensively in the live hedges bounding the sections of the 

 larger estates. It strikes root readily from stakes and, as it has proven 

 profitable in the past, ought to be propagated now, because of its eco- 

 nomic value. 



BIOLOGY.— 7/j^ Bioclimatic Law} Andrew D. Hopkins, Bu- 

 reau of Entomology. 

 In 17 18 Dr. Jacob Bigelow, who was then Rumford professor 

 and lecturer on materia medica and botany in Harvard Univer- 

 sity, published a paper- based on evidence secured from the 

 reported dates of the blooming of the peach tree at dififerent 

 places between Montreal, Canada, and Fort Clairbome in Alabama 

 Territory. In this paper Dr. Bigelow suggested that the differ- 

 ence in the time of the event between the northern and southern 

 extremes of the country was not less than two months and a 

 half. This suggestion served to stimulate further studies along 

 this line by botanists in Europe and especially in Germany, and 

 finally led to the founding of the science of periodical phenomena 

 under the designation of Phenology. 



' Read before the Biological Society of Washington, November 29, 19 19. 

 2 Memoirs Amer. Acad. Arts and Sciences 4, Part I. 



