Biologie. 611 



the t^phae which compose them. The different hyphae of the endo- 

 phyte have essentially the same structure as those composing the 

 rhizomorph Strand. The hyphae of each region show characteristic 

 alterations. They are permanent in the first region, but they undergo 

 selfdisorganization in the seeond, leaving their walls as irregulär 

 masses, while in the third region they are mostly consumed by the 

 hostcells. 



The walls of the mycorhizal cells undergo certain chemical and 

 physical changes. In the first region they become lignified and in 

 the seeond they are partry dissolved by the perforating hyphae. In 

 the third region the walls become thickened but do not undergo 

 any chemical modification. Further, in both the first and third 

 regions the wall develops a tubulär sheath which shows a distinct 

 lignin reaction. The thick walled hyphae of the first region also give 

 lignin reaction. 



In the mycorhizal cells the amount of the cytoplasm and the 

 size of the nucleus are increased previous to the infection of the 

 fungus. After infection the protoplast is soon consumed by the 

 fungus in the seeond region, but in the first region the cytoplasm 

 invests the hyphal clump and the nucleus is stretched, often so 

 much as to cause fragmentation into two portions. When the clump 

 becomes larger, the protoplast disappears entirely. 



In the third region the cytoplasm increases further in amount 

 and acquires a granulär and dense consistence, while the nucleus 

 undergoes hypertrophy, hyperchromatophily, and various deforma- 

 tions by constriction. The constricted portions may be often pulled 

 apart in a stellate form. 



In the third region there appear prominent bodies , which may 

 be considered to comprise both secretion and exeretion produets of 

 the endophyte. The development of these bodies is fully described. 

 Further, in the third region an aecumulation of very fine granules 

 is observed round the hyphae, previous to their desintegration. 

 Probably it is a phenomenon connected with the digesting action 

 of the host. 



The cell of the third region is certainly a metabolic centre of 

 the higher symbiont, where the food materials are elaborated. The 

 remarkable alterations in the cytoplasm and nucleus are indications 

 of the great activities that are going on in the cell during this pro- 

 cess; so that, when the latter is over, the nucleus resumes its ori- 

 ginal form and structure, while the cytoplasm again becomes fibrous 

 and vacuolate. 



There is no evidence that the larger secretionbodies are direct 

 derivations from the swollen portion of the fungal hyphae. They 

 are due to the aecumulation of substances secreted by the fungus 

 into the cytoplasm. 



Starch grains disappear from all the mycorhizal cells. However, 

 in the third region they reappear with the cessation of the meta- 

 bolic activity. 



The rhizomorph, besides forming m} T corhiza, behaves as a true 

 parasite towards Gastrodia, and under certain circumstances the 

 Strand penetrates deeply into the tissue of the tuber, then developing 

 as Rhisomorpha siibcorticalis. The infected tissue collapses and is 

 apparently injured , as may be seen in potatotubers attacked by 

 the same fungus. 



Gastrodia multiplies usually by the tuber. At the end of autumn 

 the daughter-tubercles are all set free separately. The association 



