MacMillan: OBSERVATIONS ON PTERYGOPHORA. 739 



I desire to express my thanks to Miss Josephine E. Tilden 

 for the winter fruiting material which she kindly collected for 

 me and for the series of slides from which most of my descrip- 

 tion has been made, and to Mr. H. L. Lyon for the photo-mi- 

 crographs reproduced in plate LXI and prepared by him at 

 my request. 



SUMMARY. 



1. Ptcrygophora calif ornica grows to a larger size than 

 generally known. Specimens ten feet in length with trunks 

 three inches in diameter have been seen. 



2. As displayed in the Straits of Fuca, Pterygophora is a 

 surge plant, growing below the zone of Lessonia and above 

 that of Nercocystis. 



3. Pterygophora may be classified either in the Laminariese 

 or the Alariideae. Its characters are in many respects inter- 

 mediate between these tribes. 



4. The holdfast shows distinct rings of growth and these in 

 most instances arise, not through morphological differences be- 

 tween adjacent cell-layers, but through differences in the cell 

 contents. The substances, which produced in greater or less 

 amount give the ringed appearance, are regarded as polysac- 

 charids allied to mucine, as described by Koch. 



5. The stipe is devoid of the mucilage ducts of Ruprecht and 

 shows distinct rings of growth, due in most instances, to the 

 juxtaposition of a layer of cells with larger lumina, upon a layer 

 with smaller. In some cases the ringed appearance of the stipe 

 seemed to be due to the same condition described for the holdfast. 



6. In the cortex of the lamina large polysaccharid idioblasts 

 are abundantly developed. These are most numerous in the 

 pinnas and are often exhausted of their contents during the proc- 

 ess of soral formation. 



7. The sori are distributed in irregular patches toward the 

 base of the pinna and in the disposition of the cuticular caps 

 upon the paraphyses suggest Lessonia. The plant fruits in the 

 latitude of Port Renfrew during the month of December. 



DESCRIPTION OF PLATE LVII. 



Young plants of Pterygophora, about one-half natural size. 



1. Plant "A" of text. 



2, 3, 4. Somewhat older plants; in 4 the midrib is just beginning 

 to appear in the base of the lamina. 



