DR. HORATIO WOOD ON FRESH WATER ALG^. 193 



handsome masses of these alg^e are rarely worth carrying home. 

 After all, however, much must be left to chance ; the best way is to 

 gather small quantities from numerous localities, keeping them 

 separate until they can be examined. 



Adhering to the various larger plants, to floating matters, twigs, 

 stones, &c., in ditches, will often be found filamentous Algae, which 

 make fine filmy fringes around the stems, or on the edges of the 

 leaves, or perchance one may meet with Rivalarise or Nostocs, &c., 

 forming little green or brownish balls, or indefinite protuberances 

 attached to small stems or leaves. These latter forms are to be 

 looked for, especially late in the season, and whenever seen should 

 be secured. 



In the latter part of summer there is often a brownish, gelatinous 

 scum to be seen floating on ditches. Portions of this should be 

 preserved, as it frequently contains interesting Nostocs and other 

 plants. 



In regard to large rivers^ the time of year in which I have been 

 most successful in such localities is the latter summer months. 

 Springs and small bodies of clear water may be searched with a 

 hope of reward at any time of the year when they are not actually 

 frozen up. I have found some exceedingly beautiful and rare 

 Alg£e in such places as early as March, and in open seasons they 

 may be collected even earlier than this. The Desmids are most 

 abundant in the spring, and possibly most beautiful then. They, 

 however, rarely conjugate at that time, and the most valuable 

 specimens are therefore to be obtained later — during the summer 

 and autumn months, at least, so it is said ; and the experience I 

 have had with this family seems to confirm it. Rivulets should be 

 watched especially in early spring, and during the summer months. 



From the time when the weather first grows cool in the autumn, 

 on until the cold weather has fairly set in, and the reign of ice and 

 snow commences, is the period during which the Algae hunter 

 should search carefully all wet, dripjnng rocks, for specimens. 

 Amongst the stems of wet mosses — in dark, damp crevices, and 

 little grottos beneath shelving rocks — is the Algje harvest to be 

 reaped at this season. Nostocs, Palmellas, conjugating Desmids, 

 Siiosiphons, various unicellular Algae, then flourish in such 

 localities. My experience has been that late in the autumn ravines, 

 railroad cuttings, rocky river-banks, &c., reward time and labour 

 better than any other localities. 



