38 University o\ California Publications in Botany [Vol. lu 



inhabit the region. These dwarfs are always found on mud flats, salt 

 marshes, and ({uite commonly at the mouths of rivers and smaller 

 streams where such mud flats and marshes may occur. At extreme high 

 tides, frequently, a great abundance of plants, of whatever species of 

 Fucus happens to be growing in the vicinity, are thrown up and lodge 

 among other plants that grow there. The spores are shed and, being 

 in a moist place, they germinate and persist for a longer or shorter 

 time. The plants are always much gnarled and distorted, and rarely 

 come to fruit. At the mouth of the Indian River at Sitka, Alaska, is a 

 favorable place for the study of such dwarfed plants. There are many 

 different forms of Fucus growing in the vicinity, and a great many 

 plants are constantly being cast up on the gradually sloping flat at the 

 mouth of the stream. There are enormous numbers of dwarfed plants 

 in all possible stages of development and distortion. One can come 

 to no other conclusion than that these are dwarfed plantvS, that they are 

 the offspring of whatever plants may by chance be thrown up there, 

 and that their identity can not be traced, growing as they do in such 

 unusually abnormal environmental conditions. 



Among these abnormal environmental conditions may be mentioned, 

 first, inconstancy in the food supply due to frequent changes in the 

 salinity of the water, resulting in great differences in the osmotic 

 tension; .second, great variation in the temperature— the fresh water 

 from the river flows over them more or less, and its temperature is 

 near the freezing point a large part of the year; third, variation in 

 light intensity; and fourth, exposure to muddy water. Under such 

 conditions it is rather a biological wonder that any forms of the genus 

 persist at all, yet many small specimens produce seemingly viable 

 spores. 



All of our forms on the Pacific coast are synoicous. This makes the 

 matter of tracing the ancestry of dwarfs slightly more difficult than if 

 dioicous forms were present, without resorting to the experimental 

 method by cultures. 



The study of these dwarfed forms of brown seaweeds has been 

 pursued quite extensively by Baker (1912'i and by Baker and Bohling 

 (1916). They traced the ancestry of certain forms and produced 

 dwarfs experimentally. Some of these forms they claim to he fixed 

 entities. They did not, however, try the experiment of producing 

 sporelings from the dwarfed forms and transplanting them to a normal 

 habitat to ascertain if they reverted at once to the oi-iginal form. 



