M. C. COOKE, NOTES ON PODISOMA. 257 



although the main facts have since been established by Tulasne 

 by examination of Podisoma Juniperi-communis, Fries. " I was 

 able," he says, " to determine that the bipartite sporidia attri- 

 buted to Podisoma were not, notwithstanding their spore-like 

 form, and their kind of germination, really analogous to the 

 ordinary spores of fungi, and that it would perhaps be more 

 exact to compare them with the quadrilocular basidia of the 

 TremellcB. These pretended spores are formed of two large 

 conical cells, opposed by their base and easily separating, they vary 

 in length between '06 and '08 of a millemetre, and measure 015- 

 •019 m.m. in their greatest transverse diameter. The membrane of 

 which they are formed is thin and completely colourless in most of 

 them, though much thicker, and coloured brown in others.* It is 

 principally the spores with thin membranes that emit from near the 

 middle very obtuse tubes, having a diameter of from -007 to -01 

 of a millimetre, and into which by degrees as they elongate the 

 contents of the parent utricles pass. Each of the two cells of the 

 supposed spore may originate near its base four of these tubes, 

 opposed to each other at their point of origin, and their subsequent 

 direction ; but it is rather rare for eight tubes (two by two) to 

 decussate from the same spore, or basidium. Usually there are 

 only two or three which are completely developed, and these tend 

 together towards the surface of the fungus, which they pass, and 

 expand at liberty in the air. The tubes generally become thicker 

 by degrees as they elongate, some only slightly exceeding the 

 length of the basidia (protospores); others attain three or four times 

 that length, according to the greater or less distance between the 

 basiclinmj (protospore), and the surface of the plant. In the 

 longest tubes it is easy to observe how the colouring matter 

 (endochrome) passes to their outer extremity, leaving the portion 

 nearest to the parent cell colourless and lifeless. When nearly 

 attaining their ultimate dimensions all the tubes are divided towards 

 their outer extremity by transverse septa into unequal cells ; then 

 simple and solitary processes of variable length and form, but at- 

 tenuated upwards, proceed from each segment of the initial tube, 

 and produce at their extremity an oval spore (teleutospore) which 

 is slightly curved and unilocular. These spores absorb all the 



* This seems to be dependent on the degree of maturity at which they may 

 have arrived. 



t This is the term employed by Tulasne for the primary spores, but we prefer 

 calling them " protospores." 



