Decembee 17, 1915] 



SCIENCE 



875 



different final expressions of a common method of 

 development. Polycotyledony was more common 

 in the primitive gymnosperms; and neither coales- 

 cence nor splitting explains the two conditions. 

 Discussion: Professors Clements and Campbell. 



Methods of Pollination and Evolution of the Male 

 Gametophyte : L. L. Buelingame, Stanford 

 University. 

 There are four types of pollination devices and 



male gametophytes found among the Gymnosperms 



as follows: 



1. The Cycadofilicales and Cordiatales male 

 gametophyte has numerous cells in its pollen grain. 

 It is as yet uncertain whether they are spermato- 

 genous or prothallial. No pollen tubes of any sort 

 were formed. The pollen grains were lodged in 

 pollen chambers in the nucellus. 



2. The Cycadales have a single prothallial cell, a 

 pollen chamber, swimming sperms and a haustorial 

 pollen tube that is probably to be homologized 

 with the rhizoid of their ancient Pteridophyte an- 

 cestors. 



3. The Araucarian conifers have a multicellular 

 prothallus, non-ciliated sperms, and a protruding 

 nucellus without a pollen chamber. The pollen 

 lodges on the ovuliferous scale at a distance from 

 the nucellus and forms a long branching haustorial 

 pollen. This tube is probably to be homologized 

 with the germ tube and not the rhizoid of their 

 pteridophytic ancestors. It is not homologous with 

 that of the cycads, since it does not have the same 

 function, grow in the same direction, and was prob- 

 ably derived from different ancestors. 



The Abietinean conifers have short direct pollen 

 tubes, two evanescent prothallial cells, and non- 

 ciliated sperms. They could readily have been de- 

 rived by reduction from the araucarian type. 

 There seems to be very little probability of the 

 reverse process, since such a course of evolution 

 would be accomplished through a number of inter- 

 mediate steps each of which is apparently dis- 

 tinctly disadvantageous to the plants adopting It. 

 Some Notes on Western Species of Cupressus: L. 



B. Abeams, Stanford University. 



Among the Californian conifers the genus 

 Cupressus occupies an important position in point 

 of interest to the botanist, and especially to the 

 plant geographer. The true cypresses belong to 

 warm temperate climates, and are associated in 

 our minds with the sunny Mediterranean countries. 

 But Cupressus is not altogether an old world 

 genus; fully half if not more of the species are 

 North American, and more are in California than 

 in any other one section. 



Turning to the geological records we find that 



in Tertiary time Cupressus flourished in Greenland 

 and northern Europe. The present far separated 

 eastern and western branches, then, like torreyas 

 and sequoias, are the remnants of a once widely 

 distributed race. The local distribution of the 

 California species, which seldom or never form 

 forests but exist in small isolated groves, is also 

 suggestive of a decadent race, once flourishing 

 but now struggling against the invaders of a new 

 age. 



Up to the present time five species have been 

 recognized in California: C. macrocarpa Hartw., 

 C. goveniana Gord., C. maenabiana Murr., C sar- 

 gentii Jepson and C. iakeri Jepson. Two remote 

 groves, little understood or unknown to those who 

 have undertaken to monograph the genus, have 

 proved after careful field studies to be distinct 

 from other Californian species. Those of San 

 Diego County, which previously have been placed 

 in goveniana, are in no way related to that spe- 

 cies, but belong to the smooth-trunked group rep- 

 resented by guadalupensis. The other, an hitherto 

 unknown grove situated in the Piute Mountains is 

 the only grove in the Sierra Nevada. This species 

 has the glandular foliage of maenabiana and 

 baTceri, but the fruit is more the nature of goveni- 

 ana. It is unquestionably distinct from these, how- 

 ever, and is to be described as a new species. 



Geologic History of the Gymnosperms: E. W. 

 Beret, Johns Hopkins University (read by 



FOREEST ShEEVE). 



Wednesday, August 4 

 Morphogenic Effects of Light: Geoegb J. Peiscb, 



Stanford University. 



Stimuli are sometimes classified as formative 

 and directive. The influence of a given stimulus 

 may be due to its quantity, the direction from which 

 it is received, etc. Then we find the quantity of 

 light exercising a distinct effect upon the quantity, 

 and inferentially upon the growth. This is plainer 

 perhaps in parts of the world where the quantity 

 of light falling upon the earth's surface is greater 

 than elsewhere, owing to the dryness and cleanness 

 of the atmosphere. The top of the forest and the 

 upper surface of the chaparral are remarkably 

 flat, despite the number of species composing each. 

 That light is a factor in determining this is shown 

 by the behavior of Escholtzia, bur clover, gera- 

 nium, mint and other plants, wild and cultivated, 

 coming up in chaparral, hedges, vines, etc. These 

 ordinarily short plants may become extraordinarily 

 long under these special conditions of light. 



The direction from which light comes also de- 

 termines the form which certain plants assume. 



