97 



PROTOPLASMIC CONTINUITY IN THE FUCACKA-l. 



By Thomas Hick, B.A., B.bc. 



(Tab. 255.) 



Previous researches* having shown that protoplasmic con- 

 tinuity obtains very widely in the Floridece, the question very naturally 

 suggested itself whether similar phenomena were to be met with in 

 other groups of Marine Algfe, and especially in the Fucaceic. To 

 supply an answer to this question, a very careful investigation of 

 the histology of the commoner Fucoids was iinder taken, and the 

 results of this form the basis of the present communication. 

 I venture to think they conclusively establish the position that 

 here too a continuity of protoplasm through the cell walls is in ex- 

 istence, which, though of a different type from that described i]^ 

 many of the Floridea, is not less certain and definite. 



As in the case of the Floridem, the materials employed have 

 been partly sun-dried and partly fresh, the former having been 

 found in the majority of cases quite as demonstrative as the latter. 



The methods of treatment adopted to render the arangements 

 for continuity perceptible have varied somewhat, owing to the fact 

 that the same treatment was not always equally successful with 

 different plants. In general terms, the trdtttment was such as would 

 either dissolve out the protoplasm from the tissues, or else swell 

 up, gelatise, or dissolve the cellulose framework. Pigments of 

 various kinds were also made use of for the usual purpose of 

 differentiating and demonstrating different structures. The dissolu- 

 tion of the protoplasm was usually effected, without any difficulty, 

 by dilute solution of common bleaching-poAvder. Greater difficulty 

 was at first experienced in swelling the sections sufficiently to 

 make clear the relation between the protoplasts and their en- 

 velopes. Schultze's solution and sulphuric acid, of themselves, 

 were found to be of little use for this purpose, though so valuable 

 in the manipulation of tissues from other plants. After a number 

 of reagents had been experimented with, alkalies were found to be 

 the most effective swelling reagents, and of these ammonia and 

 carbonate of ammonia of various strengths were decidedly the most 

 serviceable. When a greater or less amount of disintegration of 

 the tissues was desired, the sections were treated successively with 

 moderately strong sulphuric acid and strong ammonia. The 

 various ways in which the reagents were employed need not be 

 described in detail, but the following methods were so generally 

 followed, and, as a rule, furnished such favourable results, that, for 

 the guidance of those who may wish to verify the statements here 

 set forth, they may be given in full. 



A. To obtain a general view of the structure of the thallus of 

 the plant under investigation, thin sections were placed in fresh 



* British Association Report, 188;}, p. 547. ' Jouinal of Botany,' February 

 nnd Mnrch, lH84. 



Journal of Botany. — Vol. 'I'd. [April, 1885.] it 



