National Geographic : 1955 Jun
+ Eyes Scan a Bit of Rockweed for Hydroid Colonies Under the intent gaze of a young visitor, the author selects material for his photomicroscope. Portrait of a Clava colony on page 820 shows the result. Most photographs in the series were taken in labora tory tanks of this sort. © Kodachromes by Paul A. Zahl + Twin-mouthed Sea Squirts Can Spurt Fountains of Water Baglike Ciona, one of the tunicates (page 819), lives inside a thick tunic of tough material like the cellulose of plants. Anchoring itself to submerged rocks or tim bers, the sea squirt filters food from water drawn into one siphon and expelled from the other.