68 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 96. 



That the blood is capable of uniting with a quantity of urine equal to itself, so as 

 to form a firm coagulum; that the red globules do not dissolve in a coagulum so 

 formed; that an admixture of urine prevents the blood from becoming putrid; and 

 that the coagulating lymph breaks down into parts almost resembling a soft powder, 

 are facts which I believe to be new; — they may however have been before ascer- 

 tained, though I have not been acquainted with them. They are certainly not 

 generally known, and one object of the present paper is to communicate them to 

 others. These facts, considered abstractedly, may not appear of much importance; 

 but when compared with what takes place in the living body, and found to agree 

 with the process the blood undergoes in the urinary bladder, they become of no 

 small value, since they enable us to account for the symptoms that occur in that 

 disease, and lead to the most simple and effectual mode of relieving them. 



XXII. On the Fructification of the Submersed Alg<e. By Mr. Corria de Serra, 



F. R. S. p. 494. 



The light which the prevailing spirit of inquiry and observation has thrown on 

 the means of reproduction allowed by nature to vegetable beings, is not yet equally 

 diffused over all of them. Those whose simpler organization seems, when ex- 

 amined, to want some of the parts which we are accustomed to consider as essen- 

 tial to generation, continue to the present moment more or less involved in dark- 

 ness; and their fecundation, and means of reproduction, are still objects of doubt 

 and inquiry. Among them the fuci, ceramiums, ulvae, conferva?, all submersed 

 algae, are perhaps in the number 'of the less illustrated. It is probable that their 

 peculiar way of living, which requires from nature a particular modification in the 

 parts destined to reproduce them, as well as in the means of performing this opera- 

 tion, has been the principal cause of the perplexity of naturalists on this subject. 

 They have either sought for things in their ordinary form, which nature furnishes 

 to these plants under a different one, adapted to their circumstances; or they have 

 thought that she deviates from her usual ways, when she only makes use of her 

 stubborn versatility, enforcing the execution of her general plan, by the means 

 which at first sight seem to make her deviate from it. In the present memoir I 

 shall endeavour to ascertain what parts of these plants perform the sexual functions; 

 and, in order to be clear, I will first relate in a few words, what has been observed 

 and believed on this point, and proceed afterwards to the exposition of the opinions 

 which observation and the strictest analogy induce me to hold on this subject. 



Reaumur was the first naturalist who bestowed a proper attention on the fructi- 

 fication of the Fuci. Two elaborate memoirs of this great man are to be found, 

 in the Parisian Transactions, for the years 17 11 and 1712, in which he endeavours 

 to persuade us, that the vesiculae filled with small grains are the female part of the 

 fructification in the fuci, and the filamentous hairs, which are found in different 

 parts of the frons, the male organs. He examined 1 1 species of fuci, in 8 of 

 which he found grains, and only in 6 the filamentous hairs. It is unlucky for his 



